Cruise in Abnormal Law in A320

[IFLY_INDIGO]

Suppose we have a jet upset at FL 350 during cruise. We recover and now the airplane is in Alternate law in pitch, Direct law in roll, and alternate law in yaw. AP/FD/ATHR are available as usual. Would you continue the flight like before.?

[pineteam]

Yes, assuming no one was injured. Probably will descend to have a better buffet margin tho.
Are you sure you have the AP when the pitch is in alternate law? I forgot the logic about it.

[PENKO]

Bank above 125 degrees, or more than 50 degrees pitch nose up, 30 degrees nose down, less than 90 knots or more than 440 knots...I'd divert, if only to get clean underwear!

[pineteam]

HAHA Penko! Fair enough! :}

[PENKO]

Anyway, we will never get a definite answer to questions like this. It will depend on the day, the crew, the airline, the captain's wife and grandma. Welcome to the many, many grey areas of aviation (and this is one of the simpler ones). I do think you'll still have the AP, but can't provide a definite answer to that. I'm sure someone with a better photographic Airbus memory will provide that answer!

[vilas]

FCOM
In the case of an extraordinary unpredictable external event (e.g. mid-air collision) the flight parameters may go far beyond the limits of the protected envelope. In this case, specific control laws are activated to ensure aircraft recovery, and to allow a safe continuation of the flight.
Note: Abnormal attitudes cannot be reached as a consequence of recorded atmospheric disturbance. When the aircraft is involved in manoeuvres well beyond even the test pilot's flight regime injuries to aircraft more than the passengers should take precedence. There is no guarantee that the structure is intact and won't fall apart. The flight should be landed at nearest suitable airport and undergo thourough inspection. When even a hard landing beyond a limit requires inspection how can this be treated so casually. It is a very serious event. In A320 In alternate law the AP is available only for two failures i.e. all spoilers fail or all SECs fail. So it's not going to be available.

[Goldenrivett]

When the aircraft is involved in manoeuvres well beyond even the test pilot's flight regime injuries to aircraft more than the passengers should take precedence.

Phew! Good job this B747, after stalling at 40 thousand feet only rolled to 94 degrees of bank and pulled 2.3g max during recovery.
https://www.flightglobal.com/news/articles/ba-747-recovers-from-94176-bank-124460/

[FlightDetent]

Suppose we have a jet upset at FL 350 during the cruise. We recover and now the aeroplane is in Alternate law in pitch, Direct law in roll, and alternate law in yaw. AP/FD/ATHR are available as usual. Would you continue the flight like before.? Dear IFI, the person giving you these questions is not being fair to you. Call it negative training or being a smart ass, depending on the audience. Let me modify the question for clarity of my opinion:
On a flight from Kuala to Chennai, we have a jet upset at FL 350 during cruise at one hour and a half before destination. We recover and now the aeroplane is in Alternate law in pitch, Direct law in roll, and alternate law in yaw. AP/FD/ATHR are available as usual. Would you not continue the flight like before.? That's the social aspect. Penko already explained the technical one.

Whoever is asking has no aim other than give you a hard time. There's no insights or wisdom gained through that exercise.

[giggitygiggity]

Suppose we have a jet upset at FL 350 during cruise. We recover and now the airplane is in Alternate law in pitch, Direct law in roll, and alternate law in yaw. AP/FD/ATHR are available as usual. Would you continue the flight like before.?

Having an autopilot available in Alternate Law is very rarely the case. It's only possible in two specific failures; SEC 1+2+3 fault or loss of all spoilers (on the A320). I'd imagine that neither of these failures should really lead to a jet upset (but I suppose it's possible). Realistically, any likely failure leading to a jet upset would result in a degradation to Alternate Law with AP lost.

Either way, a jet upset would have probably overloaded the airframe or hurt somebody so you use that information to tell you you don't want to continue. Unless safety isn't number one in your airline, it's pretty unlikely you'd ever be happy to continue unless this happened somewhere near top of descent, but obviously you do what you need to do on the day! The upset has probably scared the hell out of the passengers, do you think they'd appreciate it if you lied and told them everything is normal and they're continuing on their maybe broken aircraft for another few hours?

[vilas]

Goldenrivette
if you call that phew what would you say to this? China airline B747 on way to San Fransisco only with loss of number 4 engine rolled -176 degrees and pitched -57degrees in a dive from 41000ft to 9800ft. He managed to land at SFO. The aircraft was a write off. Check the FAA report. These are serious things you don't continue as normal when the aircraft has gone through extreme manoeuvres.

[Goldenrivett]

Hi vilas,
These are serious things you don't continue as normal when the aircraft has gone through extreme manoeuvres.

I agree that jet upset is a serious thing - but surely the whole point of upset training is to learn how to regain control without over stressing the aircraft. In the article I referenced the "BA general manager flight operations, Lloyd Cromwell Griffiths, says that Watson's recovery of control was classic. He smoothly rolled the wings level and then pitched the nose up to regain level flight. Cromwell Griffiths says that 2.3g pitch up was applied, and the IAS did not exceed 240kt."

China airline B747 on way to San Fransisco only with loss of number 4 engine rolled -176 degrees and pitched -57degrees in a dive from 41000ft to 9800ft. He managed to land at SFO. Check the FAA report.

I believe China Airline B747 upset was crew induced after an engine flamed out at cruise FL, autopilot remained in control with no rudder applied, attempts to engine relight (way outside the relight envelop) failed, meanwhile the speed continued to decay until control was lost when the autopilot was unable to keep the wings level. (still no rudder applied) During recovery they pulled 4.8g and 5.1g, outboard elevator was torn off, a hydraulic system was lost and part of the landing gear was left extended. No wonder they diverted to SFO (destination LAX)

Hardly the best example of how to recover from a jet upset.

The aircraft was a write off.
Apparently not. According to https://en.wikipedia.org/wiki/China_Airlines_Flight_006
"After repairs were made to the plane, it returned to service on April 25, 1985. It continued in service for nearly 12 years until it was leased to China Airlines' sister company, Mandarin Airlines (https://en.wikipedia.org/wiki/Mandarin_Airlines), on January 1, 1997"