IIRC, in the old days, when climbing into fast winds, the wind speed would speed up at a rate of about 1 kts per second. Just now, near the top of climb, the wind speed suddenly started increasing at a rate of about 2-3 kts per second. I assume that this change was made during the fog fix, but I’m not sure if this is a good change, because it produces a windshear-like effect. Consider the following series of events which can cause a level 1 violation when AFK:
Weather server goes out
Plane enters jetstream
Weather server comes back
Wind speeds up, plane cannot keep up at 100% throttle and stalls
It’s a poor transition between different wind regions. I just checked the weather, and what happened was a 40-50kts increase between FL300 and 340. IF makes a hard change at FL320, whereas IRL the change is probably more gradual.
I’m saying it’s a possibility with certain planes with low max engine N1 (eg. A330) that even at full throttle it cannot achieve an acceleration of 3 knots per second. I’ve never had an AP disengage in flight.
BTW the biggest danger is actually during climb if you climb by setting a fixed throttle and engage V/S mode. I was at M.78 climbing normally, looked away for a few seconds as I crossed FL320, and I was at M.70 due to a fast wind change by about 50kts.
Hey Max! Is the problem happening at cruise too or just climb? I am wondering how you are configured (power setting/speeds/load/altitude selection). I guess I’ve kinda noticed the IAS come up randomly sometimes and dipping into overspeed range but never enough for it to be dealt with by the A/P AFK. Also never a stall under these circumstances - most aircraft climb out well above stall speed. I think I understand the problem but could someone confirm this is something IF has actually done? Anyways, happy to help troubleshoot
It happens sometimes, still, I would want to climb at minimum mach 0.80 with the A330. 0,78 takes you a bit below the point where the speed is easy to regain once lost, the best being to remain at or around point 2 in the following graph:
Now for the abrupt win speed changes, some can happen in nature, some are likely due to imperfect data or network flow. Two reasons why staying alert is needed when in the sky!
if this happens, you may be cruising with a high AOA (angle of attack) or cruising too high. The plane is too heavy for your altitude if your throttle is hitting 100% and you stall.
Windshear doesn’t exist in IF. This is a poor transition between two wind regions.
BTW I’m actually not sure if all planes in IF can accelerate at 3kts per second at full throttle at regular cruise conditions. The A330 and 380 are known for other stalling issues and a350 has low n1 cap. The operating ceiling is not defined by acceleration.
I was in a 737 lol. I mentioned A330 because it’s an aircraft in IF that goes very high in throttle if you try to match IRL altitudes and so would probably stall if winds change too fast.
And it wasn’t my climb profile, it was a sudden increase in tailwind.
Your example wouldn’t cause a violation. If it happened in the other direction and the TAS dropped by 41kts, that might require pilot intervention to prevent a stall, but in IF the pilot is not expected to be at the controls in cruise. That’s why this is a problem in IF to begin with.
The issue in IF is that winds can change by 200kts between regions if the weather server goes down (and I’m pretty sure this 2-3kts/s change I experienced was the same mechanism). That’s probably impossible IRL. Anyways, practicality over realism in this case for sure.
Err… a sudden drop of tailwind means sudden rise of headwind, then actual overspeed, here like in game. The stall happened here after pilots mismanaged the event.
The actual speed change in this RL example is 3kts/seconds (41kt in 14s = 2,92kt/s), so it definitely happens in RL at FL370.
Given this, it might be a good idea to leave more time at cruise altitude before issueing a violation, since the autothrust alone (if no pilot is awake to apply speed brakes) will need time to get things back under control.
I was refering to the possibility of this happening when the plane is flying the other way, which might actually stall the plane, and possibly cause violations in the process.
Yes, violations possible in either direction.
It might be a good idea to have a much longer overspeed warning period at cruise altitude, still. As for wind change induced stall resulting in crash and overspeed violation, I guess those should be reversable based on replay.
I never saw my plane stall on AP in cruise, though, flying every day for more than three years.
This increase in rate of change of winds was recent I believe. It would probably take a weather disconnect for a stall anyways, so it’s not likely to occur.
