Francoflier wrote:

FlyingBrit wrote:

Interesting. Have had this happen a couple times on takeoff in the 220 (admittedly new-ish to the type). ATs are armed for takeoff, however the throttles are very touchy and can be fairly easily deactivated.

That's the part I don't quite understand. Does the A/T disconnect because of jerky thrust lever movement or because of accidental pushing of the A/T disconnect switch while operating them?

Lever movement in my case, and I assume most if not all of the cases in question. With autothrottles active, they're very sensitive to being nudged which I found out a couple times rolling down the runway. I have learned to guard them a little more cautiously on takeoff, giving a touch more space between my hand and the lever.

24Whiskey wrote:

They aren’t getting deactivated. They aren’t being armed for takeoff period.

It’s not noticed until you bring the thrust up through 60% N1 and you realize A/T isn’t taking it from there. It’s just a simple whoops moment where the pilot monitoring just sets appropriate thrust manually.

Unfortunately some crews are trying to salvage the situation by engaging AT during TO roll at relatively high speeds. There’s more problems with just accidentally engaging AP, the autothrottle may not set thrust to the proper flex setting.

That’s not how the 220 is flown. The AT’s are armed at the gate, so it’s not a whoops and salvage situation.

Curious why a software update can't just inhibit AP engagement below XXX ft.

The A320 A/P engagement minimum is 100ft and works just fine.

Avatar2go wrote:

Is it possible to lockout the autopilot on the takeoff roll, or below 400 feet? Or is that not desireable for some reason?

For autolands the autopilot remains engaged until after touchdown until taxi speed is reached. For a LVO rejected landing the autopilot can remain engaged.

Crew should not be reaching up to the glare shield to engage automation like this. They should simply advance the thrust levers to the forward stop if the autothrottle were to be disengaged from what I understand to be an inadvertent small reward movement of the throttle(s) which the aircraft would have been programmed to mean the start of a rejected takeoff.

Poorpilot wrote:

That’s not how the 220 is flown. The AT’s are armed at the gate, so it’s not a whoops and salvage situation.

At my airline it is very much the way we do it.

24Whiskey wrote:

Poorpilot wrote:

That’s not how the 220 is flown. The AT’s are armed at the gate, so it’s not a whoops and salvage situation.

At my airline it is very much the way we do it.

24Whiskey, do you not arm the ATs at all before push or takeoff? If not, when do you? Genuinely curious as it's always interesting to hear how different operators fly the same aircraft.

KPTKRampy wrote:

https://simpleflying.com/airbus-a220-inadvertent-autopilot-engagement-near-misses/


I thought the FAA was going to issue a separate AD for an issue the A220 has with the engines shutting down if you pull the power back too fast. Still interesting though.

The ME 262 jet fighters in WW2 have had the same problem. Engines shut down, when throttle was pulled back too fast.

The pilots all came from piston engined fighters and they behaved different. So they had to learn.

I’m not in the know about the 220 but I do remember on the MD11 we pushed the “AUTOFLIGHT” button on the mcp to engage the A/T for takeoff. That would be an interesting nuance in the discussion. If it’s the 737 way then yes, no business pushing buttons during takeoff roll.

On a side note I wouldn’t continue the takeoff even though I agree the aircraft can be perfectly hand flown. The issue is you missed something somewhere, stop the aircraft at low speed and review the setup/re run checklists.

FlyingBrit wrote:

24Whiskey wrote:

Poorpilot wrote:

That’s not how the 220 is flown. The AT’s are armed at the gate, so it’s not a whoops and salvage situation.

At my airline it is very much the way we do it.

24Whiskey, do you not arm the ATs at all before push or takeoff? If not, when do you? Genuinely curious as it's always interesting to hear how different operators fly the same aircraft.

An experienced guess—some mgt pilot looked at the possibility of a crew arming at the the gate, then accidentally exceeding the 60% N1 during taxi and having the throttles go to TOGA. No, I didn’t do it, but often discussed at sim sessions. Sim instructors liked the scenario.

GalaxyFlyer wrote:

FlyingBrit wrote:

24Whiskey wrote:

At my airline it is very much the way we do it.

24Whiskey, do you not arm the ATs at all before push or takeoff? If not, when do you? Genuinely curious as it's always interesting to hear how different operators fly the same aircraft.

An experienced guess—some mgt pilot looked at the possibility of a crew arming at the the gate, then accidentally exceeding the 60% N1 during taxi and having the throttles go to TOGA. No, I didn’t do it, but often discussed at sim sessions. Sim instructors liked the scenario.

Yup. The only one practical reason I can think of is avoiding inadvertent AT activation during the ice shedding procedure. Which we have to do maybe 10 flights a year. I suppose if you get stuck doing ORD turns this time a year it would be more often than that.

Considering that the plane wants to taxi at 60 knots at idle thrust I can’t imagine a situation that warrants north of 60% outside of an emergency. You’d likely have a brake temp issue afterwards…

24Whiskey wrote:

Poorpilot wrote:

That’s not how the 220 is flown. The AT’s are armed at the gate, so it’s not a whoops and salvage situation.

At my airline it is very much the way we do it.

Then I stand corrected. I’m assuming you’re at DL based on your prior comments in other threads, and I’m not. I was told when going through training that all 220 operators were following a similar profile because of a potential AP arming during takeoff roll. It seemed a little far fetched to me, but I could see how someone could very easily push the wrong button- at a very critical time.

Now exceeding 60% N1 on taxi seems pretty extreme as well. If I start hitting 50%, then I start the other engine or something else is going on and I call for a tug/mx. Maybe I’m taxiing incorrectly?

According to this German article, AT cannot be armed above 60 knots below 400 AGL.

https://www.aero.de/news-44002/Das-gefaehrliche-Autopilot-Panel-der-A220.html

Is that true? Why would one reach for the glareshieldb then?

Or did these incidents happen below 60 knots and no one realized AP was engaged until early rotation?

That’s true, at 60 knots the AT goes into HOLD, which is annunciated on the PFB, which means thrust is set at whatever thrust exists at 60 knots and the AT won’t adjust thrust until airborne. HOLD also allows the pilot to go IDLE, in the event of a rejected takeoff without interference from the clutches. If AT is armed at 60% N1, the AT sets takeoff thrust. What I’d bet from experience on other Collins planes, is the AT wasn’t armed, at some point while advancing the throttles, the AT did NOT takeover and advance the throttles, consequently the thrust to Takeoff. PF calls out the lack of AT, PM tries to quickly ARM the AT and hits the wrong button. The Globals have an identical panel, by Collins, differing only in not having an AT button. We just had throttle switches to engage the AT.