H O F T E C


Home   Articles

Leave Me Alone - I Fly A 1946 Airplane
Integration Tests

by Frank Hofmann,
COPA VP/EAA Technical Counsellor

"I never fly into control zones, so I don't turn my transponder on." Or a variation - "I don't fly IFR so I don't need to do calibration checks on my equipment."

Back in 1946 there were no transponders. Likely in 2050 every aircraft will have some sort of position reporting device. As requirements change and technology advances, so must our attitudes change toward equipping our aircraft for the operational environment in which we find ourselves.

So where are we headed? If you look at the fleet composition at any GA airport you notice an increasing proportion of non-certified aircraft. This uncertified fleet is made up of ultralights, homebuilts and de-certified aircraft. Of the newly built airplanes there is a tendency toward higher performance than the J-3s and C-150s had. The extreme examples at the high end are the likes of the pressurized 300 kt Lancairs vying for airspace at FL 290. As there is increasing specialized airspace on the map, and as higher performance airplanes utilize that specialized airspace, our aircraft increasingly will be required to be equipped with specialized equipment to follow specialized procedures. Such procedures will certainly also require some specialized training.

Today, if comments from observers are to be believed, many pilots cannot fully utilize the capabilities of even their hand-held GPSs. Frequently, pilots getting a check-out at a flying club are not required to demonstrate the ability to work all the equipment installed, although they are paying for its presence in the cockpit. Surely competence must mean more than keeping an airplane from crashing, and surely an ability to deal with the installed equipment must be part of any check-out.

With the advent of automated equipment to warn pilots of other similarly equipped aircraft in proximity, pilots increasingly will rely on being warned of conflicting traffic not by their eyeballs but by their equipment.

How does a non-equipped aircraft fit into the safety picture here?

The mix of the unequipped VFR airplane flying in a VFR environment along with well equipped aircraft whose pilots are busy pushing buttons inside the cockpit is not healthy. What is our responsibility toward each other? Is it reasonable to expect that we, the pilots and the regulators, will rely increasingly on equipment to make our flying safe? Will we insist that the No.1 eyeball equipment will forever remain the sole separation standard?

There are those who think that there is no need to have their transponder checked -- that ATC will let them know if it isn't working, or if their Mode 'C' is not reporting. That may be true. However, consider the individual who doesn't have his unit checked regularly, and who has it turned on under the assumption that it is working properly. He thinks that ATC sees him and will steer other traffic away from him at his reported Mode 'C' altitude. However, if his unit is not functioning properly, ATC can neither warn him of nearby traffic nor can it separate him from other traffic at his true altitude. As well, thinking his unit is functioning properly, he expects that another aircraft equipped with a traffic alert system will be aware of his presence. However, if his unit is not functioning accurately, another aircraft's traffic alert system can neither warn of his presence nor can it take effective evasive action if the aircraft with the defective unit is at an altitude other than as reported by its Mode 'C'. Worse still, if the aircraft with a defective unit also is not in contact with ATC, again ATC cannot warn him of nearby traffic but neither can it confirm with him that he is indeed at the altitude that his system is reporting. The system only works if communications are also established. "Target 3 miles at 10 o'clock, showing 2500 feet, not confirmed," is the type of thing one hears regularly on flights. This is an unnecessarily dangerous situation.

If your aircraft is equipped with a Mode 'C' encoder (altitude reporting), the CARs 571 Appendix 'B', 571 Appendix 'F' and particularly 625 Appendix 'C', paragraph 12 -- if the aircraft is operated in Class B airspace -- dictate that the system has to be checked every 2 years. This includes any aircraft, certified or not. However, realize that aircraft equipped with traffic alert systems also use that system, and rely on it increasingly, outside controlled airspace.

In the case of a non-certified aircraft, the check of the system does require a maintenance release, but that release could be signed either by the AMO who performed the integration test, or the owner of the airplane.

Finally, we should distinguish between work done on the aircraft and work done on the bench. The preferred way to check the system is while the components are all mounted on the aircraft. If an AMO bench tests a transponder, they can issue a 24-0078 release for their test work without knowing what kind of aircraft the transponder will be installed in. A bench check does give proof of whether the transponder is putting out the appropriate signal. It does not, however, show the status of the cables and the antenna and the signal they are capable of sending. You still need to have the altitude encoder certified and an integration test done to prove that the height the encoder thinks it is at corresponds to what the altimeter says. It is no good if you are at 3000 feet and your encoder is sending out some other altitude. You run the risk of having an accident and the controller has to clear all airspace above and below where you actually are and where your encoder says you are. Such integration tests cost in the vicinity of $250 every two years.

Whether the aircraft is transponder-equipped or not, it is important to broadcast periodic Position Reports. Some -- too shy to pick up a microphone -- claim: "I don't talk on the radio, but I listen so I know where everyone else is." How many others are out there "listening" but not talking? If 100% of the pilots out there on a sunny day are listening and not talking, what is the point of listening? Why not have everyone help in collision avoidance?

Even if you don't display the latest elaborate equipment in your aircraft, the least that may be expected is that you communicate with controllers and/or advisory frequencies. The fact that we have all experienced the sudden blur of a previously unseen airplane as it whizzes by should convince us of the necessity to equip ourselves with available technology, to do good maintenance on our equipment so that we sound clear and audible, and to communicate to the best of our equipments' capability.

Top of Page

Frank Hofmann, AME
COPA Secretary and Quebec Director
Copyright © 1999