I’ve been watching the A220 lately on the tracking apps and I’ve noticed the plane is averaging 28/29 thousand feet cruising altitude while the A320 doing the exact same routes at the same time is going way higher.

Is there any limitations or specs that would explain that?

There is currently an engine speed limitation in effect above FL290 for the A220. Therefore, in order to operate above FL290 the authothrust system must be turned off.

Most operators opting to remain at or below FL290.

MarkyMark90 wrote: ↑Sat Mar 14, 2020 6:51 pm I’ve been watching the A220 lately on the tracking apps and I’ve noticed the plane is averaging 28/29 thousand feet cruising altitude while the A320 doing the exact same routes at the same time is going way higher.

Is there any limitations or specs that would explain that?

https://news.aviation-safety.net/2019/ ... incidents/

rudder wrote: ↑Sat Mar 14, 2020 7:05 pm There is currently an engine speed limitation in effect above FL290 for the A220. Therefore, in order to operate above FL290 the authothrust system must be turned off.

Most operators opting to remain at or below FL290.

Turn it off before reaching FL290. That's it. It is not difficult to operate with it off in cruise.

Or, turn it on again in cruise. It's an N1 limitation, not an AT limitation.

So why are they still staying so low? Just fly with A/T off?

Unless they are scared to... the CRJ flies up high just fine without autothrottles.

derateNO wrote: ↑Sat Mar 14, 2020 9:41 pm So why are they still staying so low? Just fly with A/T off?

Unless they are scared to... the CRJ flies up high just fine without autothrottles.

The concept of an airplane flying with no AT in cruise seems poorly understood at best.

Strangely, most seem to stay airborne.

It takes a bit more work monitoring, but you could stay a bit lower than optimal and slower to keep margins.

Even doing 4+ hour legs in the CRJ I never really noticed much extra work. A little tweak here and there, and keep an eye out for mountain wave etc. But it's not rocket science and really anyone who has a job at AC should be able to figure out how to fly with A/T off.

Is this temporary? Or part of original design? Seems crazy to me that a FBW FADEC aircraft has autothrottle issues. This is not new technology. anyone in the know care to comment?

Temporary... at least it's been since the fall. Problem with the engines.

derateNO wrote: ↑Sat Mar 14, 2020 10:50 pm Temporary... at least it's been since the fall. Problem with the engines.

Software issue.

what is the ceiling limit?

George Taylor wrote: ↑Sun Mar 15, 2020 12:48 am what is the ceiling limit?

41 000 ft.

The Q400 has no auto throttle.

I might be a little disingenuous by saying that as the Q does have software and hardware limiters to prevent the engines from exceeding propulsion limitations. It won't prevent us from exceeding airspeed limitations however.

The Q doesn't need autothrottles when you cruise in the detent... lol

It needs autoruddertrim because every time you change pitch or power settings you have to reach down and re trim the goddamn thing.

derateNO wrote: ↑Sun Mar 15, 2020 12:39 pm The Q doesn't need autothrottles when you cruise in the detent... lol

Haven't used it since summer.

From what I've heard the tolerances are VERY small.

You only have a few seconds above 94% N1 before the engine has to be borescoped prior to it's next flight AND if they find so much as a tiny little something that engine is DONE and it needs to be replaced. Companies probably did the math and figured it was easier (and cheaper) to just keep the planes at FL290 and burn more fuel rather than have to do the occasional unscheduled engine change at an out station.

Again, this is just what I've heard through the grape vine.

Engine operating limits
Above 29000 feet, the maximum N1 setting is 94% N1.
Any exceedance of more than 20 continuous seconds must be reported.

It seems that the majority of new engine programs are beset by major technical problems these days. Just look at the RR Trent debacle on the 787, the GTF on the 320NEO, and now the A220. Seems like the pinnacle of engine reliability and longevity was the CFM56. Now with increased fuel efficiency comes decreased reliability and longevity.Almost seems like they are half baked, rushed to market,or not being tested under real world conditions.

Just like modern appliances. High tech and efficient but don’t last very long.

Typical Bombardier product.

palebird wrote: ↑Fri Mar 20, 2020 3:49 pm Typical Bombardier product.

Didn't the engine come from Pratt ?

goldeneagle wrote: ↑Fri Mar 20, 2020 4:06 pm

palebird wrote: ↑Fri Mar 20, 2020 3:49 pm Typical Bombardier product.

Didn't the engine come from Pratt ?

Shh.

Software.

https://www.flightglobal.com/safety/a22 ... 58.article

Wow it's caused by resonance. Some engineer is getting fired.