2005-12-06 13:40 | fche blog flying minimum equipment dilemma
Private pilots often have the luxury of cancelling flights when something is wrong. This luxury is also a burden.
In commercial operations, the decision of whether to fly or not is to some extent taken out of the pilot’s hands. Minimum equipment lists dictate aircraft imperfections that require its grounding. Operating certificates and internal policies may impose limits on flying conditions, load, crew count and duty hours. While the desire to complete the “mission” may be strong, the PIC discretion is limited. Scheduled operators usually have procedures and equipment that make a “no go” a very rare event.
In recreational flying, it is often the other way around. Collective wisdom on amateur pilot forums like the “rec.aviation” newsgroups appears to be to cancel a flight if it “feels” wrong in any way. That is believed to be the conservative way, though it comes with the opportunity cost of experience not collected. I have indeed cancelled a bunch of trips that in retrospect could have been safely flown. Since no one else seriously depended on these trips, little harm was done.
But at this moment, I have a dilemma. There is a five-hour Hope Air mission to fly today or tomorrow. Yesterday, the Aztec decided to indicate a failed left alternator. What to do? The considerations include:
- redundancy
This airplane after all is a twin, and has two alternators. The odds of the other one dying during a trip are small. The stakes depend on other factors.
- excessive wear
If a long flight is taken with only one alternator powering everything, it would be loaded more heavily than normal, causing it greater wear and tear. Flying through icing could require such additional electrical load that could quickly exceed the capabilities of a single alternator.
- weather
If the flight requires crossing instrument conditions, the possible loss of electrical power is of much greater consequence than if it was purely visual. The weather is currently looking favourable for a mostly-VFR trip, but those are approximate, and Northern Ontario is relatively scarce in terms of diversionary airports, controller contact, and weather details.
- condition of dying alternator
Some alternator failures are mild, and have no consequences other than the above (and of course a bite out of the chequebook). Some however are nasty. It is possible for an alternator to start disintegrating, due to looseness or bent parts, and eventually shed parts into the engine compartment during flight. This would cause a bad day. To tell the current condition of the dying alternator, mechanics are looking at it as we speak. But news is slow; they are busy with other aircraft; definitive information may not come forth in time.
- alternatives for patient
There may or may not be alternative transportation available for this Hope Air patient. Just this time, contrary to David Megginson’s ground support experiences, it’s been hard to get in touch with the organization. If the mission was cancelled, a new medical appointment could take weeks or months to secure.
I suspect I missed a few, but even just these factors make the go/no-go decision complicated for this putatively recreational flyer.