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What are the NATS medical requirements?
Candidates selected for NATS Trainee Air Traffic Controller training must satisfy the medical standards required for a UK Class 3 Medical Certificate.
The Class 3 certificate is the medical certification used for:
- Student Air Traffic Controller Licence applicants;
- licensed operational air traffic controllers.
NATS currently states that applicants must undergo the initial Class 3 medical assessment in full.
Candidates must also provide complete information about:
- previous illnesses;
- injuries;
- operations;
- mental-health conditions;
- neurodevelopmental conditions;
- addictions;
- migraines;
- asthma;
- visual problems;
- current and previous medication.
The Class 3 medical is not simply a general health check.
It is an aeromedical assessment designed to determine whether a person can perform safety-critical air traffic control duties without an unacceptable risk of:
- sudden incapacity;
- impaired perception;
- impaired communication;
- reduced concentration;
- medication-related impairment;
- deterioration that could affect operational safety.
This guide explains the current high-level requirements. It cannot determine whether an individual candidate will receive a medical certificate.
Only an authorised Aeromedical Examiner, Aeromedical Centre and the UK Civil Aviation Authority can make that decision after reviewing the complete case.
When does the NATS medical assessment happen?
The medical clearance normally becomes relevant after a candidate successfully completes the NATS selection assessments.
NATS currently states that successful candidates receive a conditional employment offer subject to the relevant:
- medical clearance;
- security clearance;
- employment conditions.
Once the candidate has achieved Class 3 medical clearance, NATS can assign them to a training course and provide an employment start date.
The exact sequence may differ according to the recruitment campaign.
Candidates should follow their NATS instructions regarding:
- when the medical process begins;
- how the appointment is arranged;
- which forms must be completed;
- which documents are required;
- whether additional reports are needed;
- who pays any applicable costs.
Do not independently book an examination solely because a third-party guide recommends doing so.
NATS candidates should follow the process communicated by NATS and its authorised aeromedical providers.
What is a Class 3 Medical Certificate?
A UK Class 3 Medical Certificate confirms that the holder meets the medical standards applicable to air traffic controller licensing.
The certificate is required for the privileges associated with:
- a Student Air Traffic Control Licence;
- a full Air Traffic Controller Licence.
The medical certificate and ATCO licence are separate documents.
A person may pass the NATS recruitment assessments but remain unable to begin or continue licensed training if the required medical clearance has not been obtained.
Similarly, a licensed controller must continue to hold valid medical certification to exercise the relevant operational privileges.
Who performs the initial examination?
The UK Civil Aviation Authority states that the initial Class 3 examination must be completed at an approved Aeromedical Centre.
The examination is conducted by an authorised Aeromedical Examiner with access to the applicable aviation medical standards.
The initial appointment may take up to approximately four hours.
The assessment may take longer overall if the examiner requires:
- GP records;
- specialist reports;
- additional blood tests;
- ophthalmological assessment;
- cardiology review;
- psychiatric or psychological reports;
- neurological reports;
- functional testing;
- further CAA assessment.
The examination appointment and the final certification decision are not always completed on the same day.
What happens during the initial Class 3 medical?
The current UK CAA guidance states that the initial examination includes:
- a full physical examination;
- detailed eyesight testing;
- colour-vision assessment;
- a resting electrocardiogram;
- spirometry;
- an audiogram;
- urine testing;
- a blood test for lipids.
The examination also includes a detailed review of the applicant’s medical history.
| Assessment area | General purpose |
|---|---|
| Medical history | Identifies previous or current conditions requiring assessment |
| Physical examination | Reviews general physical health and relevant body systems |
| Eyesight examination | Assesses visual acuity, eye health and binocular function |
| Colour-vision assessment | Determines whether required operational colours can be perceived safely |
| Audiogram | Measures hearing at specified frequencies |
| Electrocardiogram | Reviews the heart’s electrical activity |
| Spirometry | Measures aspects of lung function |
| Blood pressure | Identifies hypertension or other cardiovascular concerns |
| Urine testing | Screens for relevant abnormalities |
| Blood lipids | Assesses cholesterol and cardiovascular risk indicators |
An abnormal or borderline result does not always produce an immediate refusal.
It may lead to:
- repeat testing;
- a specialist report;
- referral to a CAA medical assessor;
- additional functional assessment;
- temporary deferral while information is collected.
Medical-history disclosure
Full disclosure is one of the most important parts of the Class 3 application.
The CAA application asks about previous illnesses and medical events.
NATS also tells candidates to disclose their complete history, including matters they may believe are irrelevant.
Candidates should declare requested information about:
- childhood conditions;
- hospital admissions;
- surgery;
- fractures;
- loss of consciousness;
- neurological symptoms;
- mental-health treatment;
- medication;
- substance misuse;
- visual difficulties;
- hearing problems;
- migraines;
- asthma;
- allergies;
- sleep disorders;
- neurodevelopmental conditions;
- ongoing investigations.
A past condition is not automatically disqualifying merely because it must be declared.
However, failing to disclose relevant information can affect:
- medical certification;
- employment;
- licensing;
- professional trust;
- future medical renewal.
The examiner needs the full history to make an informed assessment.
What medical documents should you prepare?
If you have a significant medical history, the CAA advises bringing reports from your GP or treating specialist.
Useful documents may include:
- diagnosis letters;
- hospital discharge summaries;
- specialist reports;
- investigation results;
- medication history;
- treatment records;
- evidence of recovery or stability;
- recent optician reports;
- hearing reports;
- psychological or psychiatric reports where relevant.
The required report depends on the condition.
Do not ask a specialist to write a generic statement saying only that you are “fit and well”.
Aeromedical assessors may require specific information such as:
- diagnosis;
- onset date;
- symptoms;
- treatment;
- medication and dose;
- side effects;
- recurrence;
- current stability;
- investigation results;
- prognosis;
- follow-up arrangements.
Medical records and specialist reports submitted to the UK CAA must be in English.
Foreign-language reports may need to be translated into English and authenticated by a certified translator.
Does wearing glasses disqualify you?
Wearing glasses or contact lenses does not automatically prevent Class 3 certification.
The examination considers:
- uncorrected visual acuity;
- corrected visual acuity;
- refractive error;
- eye health;
- binocular vision;
- visual fields;
- ocular movement;
- colour vision;
- whether suitable correction can be used safely.
Applicants who require visual correction may receive a certificate carrying a limitation requiring them to:
- wear corrective lenses;
- carry suitable spare correction;
- comply with another condition specified on the certificate.
The exact limitation depends on the assessment.
Bring your current:
- glasses;
- contact lenses;
- prescription;
- optician report;
when requested.
Do not wear contact lenses in a way that prevents the examiner from completing the required eye assessment.
Follow the appointment instructions supplied by the Aeromedical Centre.
Refractive error and specialist referral
A higher glasses prescription does not always mean automatic rejection.
Current UK CAA guidance indicates that certain refractive findings require referral and further ophthalmological evaluation.
For Class 3 applicants, referral may be required when findings include:
- myopia exceeding approximately −6.0 dioptres;
- astigmatism exceeding approximately 3.0 dioptres;
- anisometropia exceeding approximately 3.0 dioptres;
- hypermetropia exceeding approximately +5.0 dioptres.
These values should not be used for self-certification.
The result depends on the complete ophthalmological assessment, including:
- corrected visual acuity;
- retinal health;
- binocular function;
- ocular pathology;
- stability;
- suitability of corrective lenses;
- functional performance.
A candidate outside a routine range may still be considered through specialist assessment, but certification is not guaranteed.
Colour-vision requirements
Colour perception is relevant because operational systems can use colour to communicate safety-critical information.
Initial Class 3 assessment includes colour-vision testing.
Candidates should not attempt to prepare by memorising online colour-vision plates.
Unofficial digital versions may be unreliable because results can be affected by:
- screen calibration;
- brightness;
- colour settings;
- image compression;
- ambient lighting;
- non-authentic test plates.
If a candidate does not meet the initial screening requirement, the next step depends on the current UK CAA Class 3 ATCO colour-vision policy.
Further assessment may be required to determine whether the candidate can perceive the colours necessary for safe ATCO duties.
Only the authorised aeromedical process can determine the outcome.
Do not assume that:
- one failed online plate test proves medical ineligibility;
- normal everyday colour recognition guarantees certification;
- a result from an optician replaces the aviation assessment;
- pilot colour-vision rules are identical to ATCO rules.
Hearing requirements
The Class 3 medical includes an audiogram.
The current CAA guidance lists the following maximum hearing losses for initial and renewal assessments:
| Frequency | Maximum acceptable hearing loss |
|---|---|
| 500 Hz | 35 dB |
| 1,000 Hz | 35 dB |
| 2,000 Hz | 35 dB |
| 3,000 Hz | 50 dB |
The assessment considers whether the applicant can communicate safely in the operational environment.
A hearing result outside the routine standard may require:
- repeat audiometry;
- ear, nose and throat assessment;
- specialist investigation;
- functional hearing assessment;
- CAA medical review.
Do not expose yourself to excessive noise immediately before an audiogram.
Temporary threshold changes can occur following:
- loud music;
- concerts;
- power tools;
- shooting;
- prolonged headphone use;
- industrial noise.
Follow any preparation instructions provided by the medical centre.
Heart and cardiovascular assessment
The initial medical includes a resting electrocardiogram.
The examiner may also assess:
- blood pressure;
- pulse;
- cardiovascular history;
- family history;
- symptoms;
- cholesterol;
- cardiovascular risk factors.
Further investigation may be required following findings such as:
- abnormal ECG results;
- high blood pressure;
- chest pain;
- unexplained fainting;
- palpitations;
- known heart disease;
- significant cardiovascular risk.
Additional assessment may include:
- repeat ECG;
- ambulatory monitoring;
- exercise testing;
- echocardiography;
- cardiology reports;
- other investigations requested by the CAA.
Do not attempt to hide symptoms in order to obtain clearance.
A previously investigated condition may be easier to assess when complete specialist evidence is available.
Respiratory health and asthma
The initial examination includes spirometry to assess lung function.
Candidates should disclose:
- asthma;
- inhaler use;
- hospital admissions;
- breathing difficulties;
- persistent cough;
- sleep-related breathing conditions;
- previous lung disease.
A history of asthma does not by itself provide enough information to predict the outcome.
Assessment may consider:
- severity;
- symptom control;
- frequency of attacks;
- medication;
- side effects;
- lung-function results;
- hospital treatment;
- operational risk.
NATS specifically asks candidates to disclose any history of asthma.
Neurological conditions and migraines
Candidates should disclose neurological history including:
- seizures;
- epilepsy;
- fainting;
- unexplained loss of consciousness;
- significant head injury;
- stroke or transient neurological symptoms;
- recurrent vertigo;
- neurological disease;
- migraines.
The assessment of migraine may consider:
- frequency;
- duration;
- warning symptoms;
- visual disturbance;
- neurological symptoms;
- treatment;
- medication side effects;
- impact on normal function.
A single label such as “migraine” does not determine the decision.
The Aeromedical Examiner may require a detailed history or specialist neurological report.
Mental-health conditions
NATS requires candidates to disclose their complete mental-health history.
This can include:
- depression;
- anxiety;
- panic symptoms;
- trauma-related conditions;
- eating disorders;
- self-harm history;
- psychiatric treatment;
- counselling;
- hospital admission;
- addiction;
- current or previous psychiatric medication.
A history of mental-health treatment does not automatically establish whether a candidate will be certified.
The assessment can consider:
- the diagnosis;
- symptom severity;
- recurrence;
- period of stability;
- current functioning;
- treatment response;
- medication;
- side effects;
- specialist opinion;
- risk of deterioration or sudden impairment.
The CAA may request reports from:
- a GP;
- psychologist;
- psychiatrist;
- occupational-health professional;
- other treating specialist.
Candidates should not stop treatment or prescribed medication in an attempt to pass the medical.
Any change in treatment should be made only with the appropriate treating clinician.
Autism, ADHD and other neurodevelopmental conditions
NATS expressly asks candidates to disclose neurodevelopmental conditions such as:
- autism;
- ADHD.
Disclosure does not by itself provide a complete certification decision.
The aeromedical assessment may consider:
- functional history;
- education and employment;
- attention and executive functioning;
- communication;
- associated conditions;
- treatment;
- medication;
- stability;
- individual performance;
- any additional specialist evidence.
Candidates should not conceal a diagnosis because they fear automatic rejection.
Equally, no third-party website can guarantee that a particular diagnosis will be accepted.
The decision is individual and based on the applicable CAA standards and evidence.
Medication
Candidates must disclose prescribed and non-prescribed medication.
This can include:
- regular prescriptions;
- occasional prescriptions;
- over-the-counter medicines;
- sleep medication;
- painkillers;
- antihistamines;
- antidepressants;
- ADHD medication;
- migraine medication;
- inhalers;
- herbal products;
- supplements;
- cannabidiol products.
Medication may be relevant because of:
- drowsiness;
- slowed reaction;
- altered concentration;
- dizziness;
- visual effects;
- cardiovascular effects;
- interaction with another medication;
- the medical condition being treated.
Do not assume that a medicine is acceptable because:
- it is available without prescription;
- it is described as natural;
- you have used it for years;
- it is accepted in another profession;
- it does not make you feel impaired.
Do not stop a prescribed medicine without medical advice.
The Aeromedical Examiner or CAA may need information about:
- the reason for treatment;
- dosage;
- duration;
- stability;
- side effects;
- alternative treatment;
- specialist supervision.
Alcohol and drugs
Air traffic control is a safety-critical occupation.
NATS applies strict drug and alcohol requirements and states that random testing can occur from the beginning of employment.
Candidates must disclose relevant history involving:
- drug use;
- alcohol misuse;
- dependency;
- addiction treatment;
- rehabilitation;
- current concerns.
Illegal drugs and so-called legal highs are incompatible with NATS safety-critical duties.
A candidate should not assume that withholding a historical issue is safer than declaring it.
The aeromedical and employment consequences depend on the facts, evidence and applicable policy.
Diabetes and metabolic conditions
Candidates should disclose:
- diabetes;
- pre-diabetes;
- episodes of low blood sugar;
- endocrine conditions;
- relevant medication;
- significant weight changes;
- metabolic disease.
Assessment can depend on:
- the type of condition;
- treatment;
- stability;
- risk of hypoglycaemia;
- complications;
- monitoring;
- specialist evidence;
- functional safety.
The CAA updates its aeromedical policies periodically.
A diagnosis should therefore be assessed under the current Class 3 guidance rather than an old forum post or historical rule.
Surgery, injuries and previous hospital treatment
Previous surgery or injury must be declared when requested.
Relevant examples can include:
- major fractures;
- spinal injury;
- joint surgery;
- abdominal surgery;
- head injury;
- eye surgery;
- ear surgery;
- cardiac procedures;
- neurological treatment.
The examiner may consider:
- whether recovery is complete;
- pain;
- mobility;
- medication;
- risk of recurrence;
- ongoing follow-up;
- functional limitation.
Even relatively routine events should be included when the application asks for them.
The CAA specifically advises declaring conditions such as a previous broken arm or appendicitis, even though they are not normally regarded as major medical events.
Sleep and fatigue-related conditions
Candidates should disclose conditions that may affect alertness, including:
- sleep apnoea;
- narcolepsy;
- unexplained daytime sleepiness;
- chronic insomnia;
- sleep-related medication;
- other diagnosed sleep disorders.
Air traffic controllers work in a role requiring sustained attention and may work shifts.
The assessment may therefore consider:
- treatment;
- symptom control;
- daytime alertness;
- compliance with therapy;
- specialist reports;
- risk of impaired vigilance.
Pregnancy
A certificate holder who becomes pregnant must follow the current aeromedical reporting requirements.
Pregnancy does not necessarily mean that all work stops immediately, but it can affect:
- medical-certificate status;
- limitations;
- permitted duties;
- review requirements.
The individual should notify the appropriate Aeromedical Examiner or aeromedical team and follow the advice provided.
Possible medical outcomes
The examination does not always end with a simple immediate pass or fail.
Possible outcomes include:
Fit
The applicant meets the applicable standards and receives a medical certificate.
Fit with a limitation
The applicant receives a certificate subject to a condition.
Examples can include requirements relating to:
- corrective lenses;
- review;
- monitoring;
- operational restrictions.
The precise limitation is stated on the certificate.
Referral
The Aeromedical Examiner refers the case for further review.
This may occur when:
- specialist evidence is needed;
- a result falls outside routine limits;
- the CAA must make the decision;
- a functional assessment is required.
Referral is not automatically the same as refusal.
Temporarily unfit or deferred
Certification may be delayed while:
- symptoms resolve;
- treatment stabilises;
- further tests are completed;
- medical reports are obtained;
- a recovery period passes.
Unfit
The applicant does not meet the applicable medical standard.
The examiner should explain the relevant process and whether a review can be requested.
Can you request a review?
The CAA provides a process for reviewing certain medical certification decisions.
A review normally requires:
- a completed application;
- an examination;
- an assessment decision;
- relevant medical evidence.
It is not possible to complete a meaningful appeal based only on an informal online opinion.
If assessed as unfit or if a certificate is refused, ask the Aeromedical Examiner for:
- the reason;
- the applicable standard;
- the evidence required;
- the review procedure;
- the relevant deadline.
Independent medical advice can help you understand your health, but the final aeromedical decision remains with the authorised process.
How long is a Class 3 medical valid?
The current UK CAA validity periods are:
| Age | Class 3 certificate validity |
|---|---|
| Under 40 | 24 months |
| Age 40 or older | 12 months |
The date on which the applicant reaches 40 can affect the applicable validity calculation.
Always use the expiry date printed on the certificate rather than calculating it independently.
How often are individual tests repeated?
Not every investigation is necessarily repeated at every renewal.
Current CAA guidance includes the following general intervals:
| Investigation | Current general frequency |
|---|---|
| Medical examination | At each revalidation or renewal |
| Eyesight assessment | At each medical, with comprehensive assessment when required |
| Urinalysis | At every examination |
| ECG under age 30 | At the initial examination, then generally every 48 months |
| ECG age 30 or older | At examinations thereafter |
| Audiogram under age 40 | At the initial examination, then generally every 48 months |
| Audiogram age 40 or older | Generally every 24 months |
| Blood lipids | At the initial examination and again at age 40 |
| Spirometry | At the initial examination, then when clinically indicated |
The AME may require testing earlier when clinically indicated.
Revalidation and renewal
A medical examination completed before the certificate expires is generally a revalidation.
An examination completed after expiry is generally a renewal.
The CAA currently states that revalidation or renewal of a Class 3 certificate can be completed by an appropriately rated Aeromedical Examiner.
A person whose Class 3 certificate has expired for a prolonged period may face different requirements.
Do not wait until the final day to arrange the appointment.
Allow time for:
- appointment availability;
- specialist reports;
- additional investigations;
- CAA referral;
- administrative processing.
Decrease in medical fitness
A medical certificate confirms fitness at the time and under the conditions of its issue.
It does not remove the holder’s duty to report a later change.
A trainee or controller should seek aeromedical advice following matters such as:
- significant illness;
- injury;
- surgery;
- new medication;
- medication dosage changes;
- pregnancy;
- hospital admission;
- new mental-health symptoms;
- loss of consciousness;
- visual or hearing change;
- neurological symptoms;
- any condition that may affect safe performance.
The CAA states that a certificate holder who becomes aware of a decrease in medical fitness that may affect licence privileges must inform their Aeromedical Examiner.
NATS also requires employees taking new medication to inform the appropriate operational and aeromedical contacts.
Do not continue safety-critical duties while uncertain about medical fitness.
Follow the official reporting procedure.
How to prepare for the appointment
Complete the questionnaire honestly
Read every question and provide complete information.
Do not omit a condition because:
- it occurred many years ago;
- you believe it was minor;
- you have recovered;
- no medication is currently used;
- you are concerned about delay.
Gather relevant reports
Request supporting documentation early.
Specialist appointments and historical records can take time to obtain.
Bring visual correction
Bring:
- glasses;
- contact lenses;
- spare correction where requested;
- current prescription;
- recent optician report if relevant.
Bring identification and required records
Follow the appointment instructions regarding:
- photo identification;
- medical-record account;
- forms;
- previous certificates;
- specialist reports;
- medication list.
List all medication
Record:
- medicine name;
- dose;
- frequency;
- reason;
- prescribing clinician;
- start date;
- side effects.
Include non-prescription products when requested.
Avoid preventable temporary influences
Follow the medical centre’s instructions concerning:
- food;
- caffeine;
- exercise;
- contact lenses;
- alcohol;
- medication;
- hearing-test preparation.
Do not stop prescribed treatment unless instructed by the treating clinician.
Allow enough time
The initial medical can take several hours.
Do not schedule an important commitment immediately afterwards.
After you understand the medical pathway, you may still need aptitude preparation for earlier recruitment stages. You can also review Prepare for the NATS aptitude assessments that sit alongside medical clearance.
Affiliate disclosure: We may receive a commission if you purchase through this link, at no additional cost to you. ATC Practice is an independent third-party preparation provider and does not guarantee the exact assessment content used by NATS. It is not a source for medical fitness decisions and cannot replace CAA or Aeromedical Examiner advice.
Common misconceptions
“Perfect eyesight is required”
Corrective lenses can be compatible with Class 3 certification.
The assessment considers corrected vision, eye health and functional safety.
“Wearing glasses means automatic failure”
It does not.
A limitation requiring visual correction may be applied.
“One failed online colour test means I cannot become a controller”
Online colour tests are not a valid substitute for the authorised aeromedical assessment.
“Any mental-health history causes rejection”
A diagnosis alone does not provide the complete answer.
Certification depends on the individual history, current condition, treatment, stability and applicable standards.
“ADHD or autism should not be declared”
NATS expressly asks candidates to disclose neurodevelopmental conditions.
Deliberate omission can create serious employment and licensing problems.
“Prescription medication is always acceptable”
A legally prescribed medicine can still affect alertness, cognition or medical certification.
Every relevant medication must be assessed.
“Prescription medication is always disqualifying”
This is also incorrect.
The outcome depends on the medicine, condition, dose, stability, side effects and current CAA policy.
“Passing once means no more medical examinations”
Class 3 certification must be revalidated or renewed throughout the career.
“A GP can guarantee that I will pass”
A GP can provide valuable medical evidence but does not issue the aeromedical certification decision unless separately authorised for the applicable aviation role.
“Not declaring an old condition avoids complications”
Deliberate omission may be more serious than the condition itself.
Limits of this guide
This page can explain:
- the Class 3 requirement;
- the general examination process;
- the main tests;
- disclosure responsibilities;
- certificate validity;
- renewal obligations.
It cannot:
- diagnose a condition;
- determine individual fitness;
- interpret personal test results;
- guarantee certification;
- replace an Aeromedical Examiner;
- replace the UK CAA;
- advise a candidate to stop medication;
- predict the effect of a diagnosis without the complete medical record.
Candidates with a specific concern should use the authorised aeromedical process and discuss medical treatment with their own clinician.
What to verify officially
Before beginning the medical-clearance process, verify:
- whether NATS has instructed you to begin;
- who will arrange the examination;
- the authorised Aeromedical Centre;
- the required medical-record account;
- the appointment date;
- required identification;
- required forms;
- specialist evidence;
- visual-correction instructions;
- medication-reporting requirements;
- whether fasting or other preparation is required;
- how results will be communicated;
- who handles additional investigations;
- the process for workplace adjustments;
- the process for a deferred decision;
- the review procedure;
- certificate validity;
- future revalidation requirements.
Use the following as primary sources:
- the official NATS Trainee Air Traffic Controller page;
- the UK CAA initial Class 3 medical guidance;
- the UK CAA medical certification section;
- your NATS candidate instructions;
- your authorised Aeromedical Examiner.
Current official instructions always take priority over an independent guide.
Bottom line
NATS Trainee Air Traffic Controller candidates must obtain the relevant UK CAA Class 3 medical clearance before entering the licensed training pathway.
The initial assessment includes:
- medical-history review;
- physical examination;
- eyesight and colour-vision testing;
- hearing assessment;
- ECG;
- lung-function testing;
- urine testing;
- blood-lipid testing.
Candidates must disclose their complete history honestly, including:
- illnesses;
- injuries;
- mental-health conditions;
- neurodevelopmental conditions;
- addiction history;
- migraines;
- asthma;
- visual problems;
- medication.
A diagnosis, glasses prescription or historical condition does not by itself provide a final decision.
The complete evidence must be assessed under current CAA standards.
Once issued, the Class 3 certificate must remain valid and any relevant decrease in medical fitness must be reported.