RadAlt over forest
Joined: Dec 2003
Posts: 2,349
Likes: 845
From: Tring, UK
I've had the "1,000" call several times on the 777 during RVSM ops. with the radalt ramping through 1,000'. It was silent on the real approach after that.
Also had a "Too low: gear" at 37,000' but I've no idea how that was triggered.
Also had a "Too low: gear" at 37,000' but I've no idea how that was triggered.
Joined: Mar 2001
Posts: 4,563
Likes: 35
From: I wouldn't know.
Just flying the old rusty 737, both classics and NGs. Had it happen in both variants (well, -500, -300, -700 and -800). Most of the time its someone same direction 1000ft below, but it can happen (very very rare indeed) with opposite traffic if its dead center below. And that happens quite often with the current navigation performance of most airliners.
Joined: Jan 2000
Aviation Qualifications: ATPL
Posts: 29
Likes: 0
From: USA
The EGPWS used on the Airbus aircraft I fly incorporates system logic that is designed to minimize nuisance Mode 4B warnings during aircraft overflights. Without going into too much detail, the system looks at aircraft speed, configuration, and the rate of change of the radio altitude. You could still get a warning if your overflight involved an aircraft that was less than 800 feet below you.
This same system incorporates additional logic to minimize nuisance Mode 2 warnings due to loss of radio altitude tracking, which sometimes occurs during departures and arrivals in heavy rain.
Years ago, on aircraft with the first generation GPWS, nuisance warnings were commonplace. The latest generation systems generate very few nuisance warning of any kind. Thanks to the EGPWS, there have been a substantial number of documented saves. The engineers involved with the design of the EGPWS have my deepest respect.
I apologize for the thread creep.
Best regards,
The Kid
This same system incorporates additional logic to minimize nuisance Mode 2 warnings due to loss of radio altitude tracking, which sometimes occurs during departures and arrivals in heavy rain.
Years ago, on aircraft with the first generation GPWS, nuisance warnings were commonplace. The latest generation systems generate very few nuisance warning of any kind. Thanks to the EGPWS, there have been a substantial number of documented saves. The engineers involved with the design of the EGPWS have my deepest respect.
I apologize for the thread creep.
Best regards,
The Kid
Joined: Jan 2005
Posts: 2,315
Likes: 10
From: France
Aztec Kid,
I would prefer what you call "nuisance warnings" at 25,000ft, which at least tell you the system still works, to a nerd fudzing around with the 'logic' so much, that the next time a real EGPWS warning gets inhibited, because "it looked like a nuisance warning".
Keep It Simple, Stupid!
So far, it doesn't sound as if we're too far down that road yet, from what you're saying.
CJ
I would prefer what you call "nuisance warnings" at 25,000ft, which at least tell you the system still works, to a nerd fudzing around with the 'logic' so much, that the next time a real EGPWS warning gets inhibited, because "it looked like a nuisance warning".
Keep It Simple, Stupid!
So far, it doesn't sound as if we're too far down that road yet, from what you're saying.
CJ
