Compass Backlight: required or not?

[Flightcap]

Hey all,

I've been mulling over the magnetic compass backlight for a few days after messing up this question on an interview (I think).

Here's the setup: all aircraft dome lights work, both pilots have operable flashlights, passengers boarded, etc. etc. Captain goes to hit the starter and you see the magnetic compass backlight is burnt out. The rest of the compass works fine. Can you launch?

Refer to part 91.205, which states that required instruments and equipment must be in an operable condition. It also states that a magnetic direction indicator is required equipment. It does not, however, specifically state the backlight.

So, if I understand my own question, what I am concerned with is whether the backlight is considered part of the magnetic direction indicator if installed? Will failure of this component render the instrument legally unfit for flight?

Thanks in advance!

[1jz]

As far as I recall compass integral lighting is a must for night operations.

[BOAC]

I'm no sure what effect the lack of 'current' will have on the Compass deviation either.

[Intruder]

Even 25.1381 (Airworthiness for transport category airplanes) does not specify the type of lighting required. I assume that under Part 91, the instrument is "operable" if cockpit lighting is sufficient for you to read it.

[Flightcap]

Interesting stuff, thanks for the input. I said that I would choose not to launch and didn't get the job - one of my buddies who said that he would go ahead with the flight got the job. I don't know if this was what made the difference, of course, but it seems like a gray area....

[Tinwacker]

Sorry for your loss...

A quick look in the MEL during the starting time would have assisted your career answer and if really concerned a call to maintenance control.
Risk management:
How often do you use the magnetic compass, all lights working and flash lights were available???
Light shouldn't effect the compass operation as that is probably switchable.
Not knowing your type but this could be a cat 'C' item ten days to fix.

Double checking when in the office tonight...

[Flightcap]

Tinwacker,

Good perspective. As a new entrant to the field not having flown with an MEL before, I didn't consider that option during the interview. It does, of course, make a lot of sense. Not required by 91.205? Not required by an MEL? Not ano-go item. Sound logic. Is there anything in a company's op spec that might apply to this kind of issue? (For my future interview preparedness!)

[glendalegoon]

maybe you didn't get the job because of your answer. but you didn't get the job because you didn't know what an MEL was.

It is always a good answer to say: I plan to comply with the regulations, ops specs, limitations and MEL. Do you have a copy of the documents so I can give you an intelligent answer.

There are also corrections in the logbook or on the compass correction card to compensate for the electrical magnetic fields of radios, windshield heat (if compass is near windshield) and other things.

I was once asked: what would you do if the wx forecast was for good wx and you didn't have to file an alternate but you got to San Francisco and the airport was below minimums, what would you do?

I said I would fly three minutes to Oakland and land there.

I then asked what was wrong with the forecast and further details and then asked: WHAT DID YOUR GUY DO? (this is a giveaway, they are asking YOU if you are smarter than a dumb guy they already hired).

THEIR GUY declared an emergency and landed below minimums.

oh, and there was another question on an approach plate to Santa Maria Airport in california. The apch stated: RADAR REQUIRED.

So, THEIR guy turned on the weather radar.

This was not the right answer.

I got the job, but left soon for a real airline.

[Flightcap]

glendalegoon, thanks for your thoughts. I've been asking around and have found a pattern of every guy who chooses to down the aircraft not getting the job (and vice versa). Guess I should have thought of the question more in the context of an airline operation and less in the context of my part 91 flight training experience!!

I'll know for next time. At any rate, these interviews are good experience. Someday there will be more on the table than a C208 FO job.

[Intruder]

After 5 years at my first airline, I was spring-loaded to the "check the DDG/MEL" response, but it seems like a poor reason to fail an interview if you had never worked at an airline before...

FWIW, the 744 DDG goes along with the idea that an individual light can be inop, as long as the instrument is usable:

Individual lights may be inoperative provided remaining lights are:
a. Left and right flight deck dome lights operate normally.
b. Sufficient to clearly illuminate all required instruments, controls and other
devices for which it is provided.
c. Positioned so that direct rays are shielded from flight crewmembers eyes.
d. Lighting configuration and intensity is acceptable to the flight crew.

[Tinwacker]

Just got round to it, an extract from the A330 MEL with no supporting requirements.

Standby Compass Lighting
34-22-02A

Repair interval(C) - Nbr installed(1) - Nbr required(0) - Placard(No)

May be inoperative.