AF 477

By lex, on May 24th, 2011

I honestly don’t know what’s more surprising, 1) the fact that Air France 447′s CVR and DFDR were found and recovered two miles deep, two years after the plane crashed, 2) the fact that useful data could still be extracted from them, or 3) the fact that, faced with a complex, multiple emergency, none of the three airline transport pilot rated aircrew apparently had the wherewithal to actually drive the bus: **

Ultimately, despite the fact that primary cockpit displays functioned normally, the crew failed to follow standard procedures to maintain or increase thrust and keep the aircraft’s nose level, while trouble-shooting and waiting for the airspeed sensors and related functions to return to normal, according to these people.

Slated to be disclosed by investigators on Friday, the sequence of events captured on the recorders is expected to highlight that the jet slowed dangerously shortly after the autopilot disconnected. The pilots almost immediately faced the beginning of what became a series of automation failures or disconnects related to problems with the plane’s airspeed sensors, these people said.

The crew methodically tried to respond to the warnings, according to people familiar with the probe, but apparently had difficulty sorting out the warning messages, chimes and other cues while also keeping close track of essential displays showing engine power and aircraft trajectory.

It’s true that the principal task of a modern airline pilot is to take the airplane off, land it and manage all of the systems in between those two events; there’s not a lot of stick and rudder time involved when the wheels are up, and most of your “flying” is done with keypad entries and heading bugs. That said, attitude control is always critical in instrument conditions, and airspeed can be inferred from throttle settings when the pitot tubes ice up. Keep the wings level, give her an appropriate power setting and she’ll fly.

In Naval Aviation training, the mantra for task prioritization was “aviate, navigate, communicate.” The USAF had a nifty memory device for dealing with aircraft emergencies which I personally adopted: “First, maintain aircraft control. Second analyze the situation. Third, take the appropriate action.” The point of both mnemonics was that task number one was constant and recurring – you have to fly the machine.

I hate to be critical of those not here to defend themselves, but it’s a long way down from 35,000 feet.

While the preliminary report’s emphasis was on pilot error, there are systemic issues to address as well:

According to the 2009 report published by investigators after the crash, experts examined 13 other incidents of airspeed-sensor malfunctions on Airbus widebody jets at cruise altitudes. During most of those global incidents—none of which resulted in a crash—both the autopilots and automated engine-thrust systems disconnected on their own, and it took many of the flight crews up to a minute to manually adjust engine thrust…

Investigators began focusing on pitot problems from the start, because Flight 447′s automated maintenance system broadcast 21 separate messages related to such malfunctions during roughly the last four minutes of the fatal flight. But the final report, which may not be released until 2012, also is expected to delve deeper into how European air-safety regulators dealt with persistent reports of pitot-tube icing prior to the crash.

The previous interim report indicated that in late March 2009, less than three months before the crash, European aviation regulators decided that the string of pitot-icing problems on widebody Airbus models wasn’t serious enough to require mandatory replacement of pitot tubes.

Air France Flight 447′s 228 passengers and crew could not be reached for comment.

**  10-26-2018 Original link gone; replacement found – Ed.

Back To The Index

1 Comment

Filed under Best of Neptunus Lex, Carroll "Lex" LeFon, Carroll LeFon, Flying, Neptunus Lex

One response to “AF 477

  1. Pingback: A Simple System with Profound Consequences | The Lexicans

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s