BMAX Captain reported an autopilot anomaly in which led to an undesired brief nose down situation.
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Autopilot was disconnected and flight continued to destination. Airport : ZZZ. Class C : ZZZ. Flight Crew : First Officer Qualification. Accession Number : Analyst Callback : Attempted. Aircraft Equipment Problem : Critical Detector. Flight Crew : Regained Aircraft Control.
Day 3 of 3 departing in a MAX 8 after a long overnight. The aircraft accelerated normally and the Captain engaged the "A" autopilot after reaching set speed. I called "descending" just prior to the GPWS sounding "don't sink, don't sink. The remainder of the flight was uneventful. We discussed the departure at length and I reviewed in my mind our automation setup and flight profile but can't think of any reason the aircraft would pitch nose down so aggressively.
B MAX First Officer reported that the aircraft pitched nose down after engaging autopilot on departure. This is not about the automatic controls but about Max documentation in general.
- Encountering the Mind;
- THE RIVER RUNS RED: Seventh in a Series of Jess Williams Westerns (A Jess Williams Western Book 7)?
- Im Netz der braunen Spinne (German Edition).
- Airborne Saga.
Flight Crew : Captain Qualification. Total : Experience. Last 90 Days : Experience. This was the first flight on a Max for both pilots. Unfamiliarity with flight deck displays led to confusion about display annunciations and switch function. The Flight Manual does not address at least one annunciation, or the controls for the display—or if it does, neither pilot could find the explanation. I have spent literally days looking for an explanation, could not find one, and that is why I wrote this report.
It shouldn't be this hard to figure out what I'm looking at. We both saw it, couldn't find any immediate explanation for it on the ground, and didn't address it until airborne. We spent the entire hour flight trying to find the meaning of this annunciation and came up empty handed. We determined to check it out once we landed if the light came on again. We called Maintenance to check out the light. We waited to make an ELB entry, unsure if one was required.
Turned out, an ELB entry was not required. The mechanic explained the light was part of a menu for maintenance use only on the ground. In addition, there are two selector knobs that are under-explained i. These knobs don't seem to work in flight. The First Officer offered to hit the SEL function in flight, to test it out, but I thought something irreversible or undesirable might happen not knowing what we were actually selecting , so we did not try it out in flight.
The mechanic later explained SEL on the First Officer side was used on the ground by maintenance to toggle between the maintenance functions. I forgot to ask what my side did, and still don't know. Finally, in the Captain's preflight procedure in the bulletin, it says, "Selector What selector is this referring to? Is this the same selector under the Fuel Flow switch, which is shown in the MAX panels on the L position, as if that is the normal position?
This is very poorly explained. I have no idea what switch the preflight is talking about, nor do I understand even now what this switch does. I think this entire setup needs to be thoroughly explained to pilots. How can a Captain not know what switch is meant during a preflight setup?
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Poor training and even poorer documentation, that is how. It is not reassuring when a light cannot be explained or understood by the pilots, even after referencing their flight manuals. I envision some delayed departures as conscientious pilots try to resolve the meaning of the MAINT annunciation and which switches are referred to in the setup. BMAX Captain reported confusion regarding switch function and display annunciations related to "poor training and even poorer documentation". The recently released MAX8 Emergency Airworthiness Directive directs pilots how to deal with a known issue, but it does nothing to address the systems issues with the AOA system.
The MCAS function commands nose down stabilizer to enhance pitch characteristics during steep turns with elevated load factors and during flaps up flight at airspeeds approaching stall. MCAS is activated without pilot input and only operates in manual, flaps up flight. The system is designed to allow the flight crew to use column trim switch or stabilizer aisle stand cutout switches to override MCAS input. The function is commanded by the Flight Control computer using input data from sensors and other airplane systems.
The MCAS function becomes active when the airplane Angle of Attack exceeds a threshold based on airspeed and altitude. Stabilizer incremental commands are limited to 2. The magnitude of the stabilizer input is lower at high Mach number and greater at low Mach numbers. The function is reset once angle of attack falls below the Angle of Attack threshold or if manual stabilizer commands are provided by the flight crew. If the original elevated AOA condition persists, the MCAS function commands another incremental stabilizer nose down command according to current aircraft Mach number at actuation.
This communication highlights that an entire system is not described in our Flight Manual. This system is now the subject of an AD. I think it is unconscionable that a manufacturer, the FAA, and the airlines would have pilots flying an airplane without adequately training, or even providing available resources and sufficient documentation to understand the highly complex systems that differentiate this aircraft from prior models. The fact that this airplane requires such jury rigging to fly is a red flag.
Now we know the systems employed are error prone--even if the pilots aren't sure what those systems are, what redundancies are in place, and failure modes. I am left to wonder: what else don't I know? The Flight Manual is inadequate and almost criminally insufficient. It involves automatic thrust control, which also might have been involved in the Lion Air crash. Flight Crew : Pilot Flying Function. Flight Crew : Multiengine Qualification. Accession Number : Human Factors : Confusion. Deviation - Speed : All Types Anomaly. Flight Crew : Overcame Equipment Problem. After feet I noticed a decrease in aircraft performance.
I picked up that the autothrottles were not moving to commanded position even though they were engaged.
I'm sure they were set properly for takeoff but not sure when the discrepancy took place. My scan wasn't as well developed since I've only flown the MAX once before. I manually positioned the thrust levers ASAP. This resolved the threat, we were able to increase speed to clean up and continue the climb to feet. Shortly afterwards I heard about the other carrier accident and am wondering if any other crews have experienced similar incidents with the autothrottle system on the MAX? Or I may have made a possible flying mistake which is more likely.
When the dust settles who will remain?