In short
- Transponder: every installed transponder, including its altitude reporting, must be tested at least every 24 months, VFR or IFR.[1]
- Altimeter and static system: must be calibrated at least every 24 months if you fly IFR, or VFR in Class B or C airspace, or Class D airspace designated as transponder airspace.[2]
- How it's tested: to Standard 571, Appendix B (altimeter and static system) and Appendix F (transponder).
- Who does it: altimeter tests have to be done by an approved maintenance organization. Katz Avionics is AMO 93-08, with Transport Canada ratings that include Pitot-Static instruments and Radio systems.
- Records: the test date and the maximum altitude tested go on the altimeter and into your aircraft record.
Do I need it?
| How you fly | Transponder test, every 24 months | Altimeter and static system, every 24 months |
|---|---|---|
| VFR only, never in Class B or C airspace, or Class D airspace designated as transponder airspace | Yes, if a transponder is installed | Not required by item 13 |
| VFR in Class B or C airspace, or Class D airspace designated as transponder airspace | Yes | Yes |
| IFR | Yes | Yes |
Transponder airspace is all Class A, B and C airspace, plus any Class D or E airspace designated as transponder airspace in the Designated Airspace Handbook.[3] To fly in it, your aircraft needs a transponder and automatic pressure-altitude reporting equipment.[4]
If your aircraft is maintained under an approved maintenance schedule (for example, by an air operator), that schedule may set different requirements. Check it, or ask us.
Why it matters
Your transponder tells ATC your altitude, and that altitude comes from static pressure, through an encoder or an air data computer. A leak in the static system, or an altimeter that reads wrong, can put the altitude you fly and the altitude ATC sees out of step. The 24-month checks are there to catch that on the ground.
What we test
Each check follows Transport Canada's Standard 571. In plain terms:
Static system
The static system brings outside air pressure to your altimeter and other instruments.
Details on the static system
- We check it's free of water and blockages, with any port heater working.
- A leak test: on an unpressurized aircraft, the altimeter can't lose more than 100 ft in a minute.
Altimeter
We run it through a set of test altitudes, up to the highest your aircraft normally flies.
Details on the altimeter
- It has to read accurately going up and coming down, return to where it started, and not stick.
- Its case has to be sealed, and the baro-setting window has to agree with what it shows.
- Glass panels and air data computers are tested to the manufacturer's procedure.
Transponder and encoder
We check it hears ATC radar and replies on the right frequency, at the right power, and only when it should.
Details on the transponder and encoder
- Mode S units are also checked for their aircraft address and replies.
- The altitude it reports has to match your altimeter within 125 ft.
The full list of tests and limits is in Standard 571, Appendix B (altimeter and static system) and Appendix F (transponder).
What you get back
- A label on the altimeter showing the test date and the maximum altitude tested.
- An entry in your aircraft record, made by the person signing the maintenance release.
- We keep your results on file: what we found and what we recorded, so your next inspection starts from your aircraft's history.
Planning your visit
- Find your due date. Check your aircraft records for the last transponder and altimeter test entries, and the label on the altimeter. The interval is a maximum: "intervals not exceeding 24 months".
- Book both together if you need both. The altitude-reporting check compares your encoder or air data computer against the altimeter, so one visit covers it.
- Glass cockpit or air data computer? Give us the make and model when you book, so we have the manufacturer's procedure ready.
- While it's in: your ELT has its own schedule. With a standard (non-water-activated) battery, a 121.5 MHz ELT is due every 12 months, and a 406 MHz ELT needs an operational test every 12 months and a performance test every 24 months.[5]
Questions owners ask
I only fly VFR. Do I still need the transponder test?
Yes, if a transponder is installed. Item 14 of Standard 625, Appendix C applies to every installed transponder, with no exception for VFR flying.
Do I need the altimeter calibration if I only fly VFR?
Only if you fly in Class B or C airspace, or Class D airspace designated as transponder airspace (item 13 of Standard 625, Appendix C). The transponder test is still due either way.
How do I know when they're due?
Your aircraft record shows the date of the last test, and the altimeter carries a label with the test date and the maximum altitude tested. Each check is due no more than 24 months after the last one.
Who can do these tests?
Standard 571, Appendix B says altimeter tests have to be done by an approved maintenance organization. We're AMO 93-08, and our Transport Canada ratings include Pitot-Static instruments and Radio systems.
What if something doesn't pass?
We track down the cause, show you the readings, and quote the repair before going further.
My aircraft is on an approved maintenance schedule. Is it different?
It can be. An approved maintenance schedule may set different requirements, so check yours, or send it to us and we'll go through it with you.
Book your 24-month inspection
Tell us about your aircraft and we'll come back with a quote.
Sources
- Transport Canada, Standard 625 Appendix C, Out of Phase Tasks and Equipment Maintenance Requirements (items 12, 13 and 14; paragraphs (2) and (3)): tc.canada.ca, Standard 625 Appendix C
- Transport Canada, Standard 571 Appendixes A to M (Appendix B, Altimeter System Test and Inspection; Appendix F, ATC Transponder Performance Tests): tc.canada.ca, Standard 571 Appendixes A to M
- Canadian Aviation Regulations, section 601.03 (transponder airspace): laws-lois.justice.gc.ca, CAR 601.03
- Canadian Aviation Regulations, section 605.35 (transponder and automatic pressure-altitude reporting equipment): laws-lois.justice.gc.ca, CAR 605.35
This guide summarizes the Canadian Aviation Regulations as of 5 November 2026. The regulations and your aircraft's maintenance schedule are the authority, and as owner you're responsible for determining which requirements apply to your aircraft (Standard 625, Appendix C, paragraph (3)).