Peocedures for lost altimeters

[Denti]

Quite a few other reasons for wrong or malfunctioning altitude information besides static ports. We had quite a few cases of malfunctioning AoA vanes a couple years ago and in all cases not only IAS but also altitude was missing or completely wrong (as well as G/S and W/V). And that on such a simple aircraft as the 737NG.

[BOAC]

Your standby did not work??????

[Denti]

Of course it did, no AoA vane input into the ISFD. And of course the ISFD has its own set of static ports as well. Interesting though that all incidents started either as ALT DISAGREE or IAS DISAGREE, not AOA DISAGREE. Anyway, my point was that there are some other sources for an altimeter malfunction than just simply blocked static ports.

[BOAC]

Originally Posted by denti

and in all cases not only IAS but also altitude was missing or completely wrong

- it seemed to prompt the question

[orgASMic]

Schiphol airliner crash blamed on altimeter failure, pilot error - Wikinews, the free news source

This accident was blamed on altimeter failure leading to a CFIT because the autopilot believed the faulty altimeter and the crew noticed too late to intervene. The aircraft had a history of altimeter failure that had not been picked up.

My take on this emergency (it is a Mayday IMHO) would be to separate the aircraft laterally and get a shepherd aircraft (probably a friendly military crew, as they are used to flying in formation and will not have company issues to worry about) on him PDQ, whatever the flight conditions, then use the shepherd to escort him down the nearest ILS/PAR.

[BOAC]

org - best not to confuse radio altimeters (Schiphol) with what this discussion is about? Your plan is good, though