MD-11 flight crew reported unreliable airspeed and pitch indications on climb out. The flight crew elected to monitor the airspeed and pitch carefully and continued the flight to destination airport.
Synopsis
MD-11 flight crew reported unreliable airspeed and pitch indications on climb out. The flight crew elected to monitor the airspeed and pitch carefully and continued the flight to destination airport.
Narrative
The incident occurred around 100 feet AGL on takeoff from Runway XX at ZZZZ; shortly after I requested 'Positive Rate; Gear Up;' on a seemingly normal takeoff with no prior unusual circumstances (including a relatively calm wind situation). I FIRST/INITIALLY encountered the stick shaker and was still in the process of pitching up to full climb ANU (Aircraft Nose Up). I believe it occurred around 15-17 degrees ANU. A moment later the A/S (Airspeed) tape went from Normal/White indication to the bottom of the Amber foot; on the edge of Red. I immediately began lowering the nose to 10 degrees to treat the incident as a potential Airspeed Unreliable condition; but as I did; the PLI (Pitch Level Indication) changed from Blue/Cyan to Red and moved rapidly down onto the pip on my Attitude Indicator (the FD Pitch bar still commanding increased pitch above the PLI). To my knowledge I held a pitch around 12 degre the edges of Amber/Red to overspeed indications briefly; while the red PLI continued indicating on top of the aircraft pip - stick shaker still activating. What seemed like several seconds later; a LVL2 'SLAT DISAG' appeared on the Engine Display with the associated amber annunciations on the Flap/Slat section of the PFD (Primary Flight Display). All indications returned back to normal. The aircraft appeared to be operating normally; and we continued our flight without incident until approach to landing into ZZZZ1. When I commanded 'Slats Extend;' we briefly noticed a spurious LVL2 'SLAT DISAG' indication on the Engine Display again. All other indications were normal after this. We continued the approach to landing without further incident.Immediate Crew Awareness/Immediate Crew Action.We notified Maintenance Control via ACARS and made the appropriate logbook entry.Proper maintenance procedures: regarding this issue; Aircraft X has had multiple write-ups from several crew members; for several months.
Second reporter narrative
We were cleared for takeoff Runway XX at ZZZZ. Takeoff roll and rotation was normal. Passing 100 ft. AGL we were at approximately 175 knots; suddenly we felt the stick shaker and the airspeed tape began to oscillate rapidly; the airspeed didn't change much but the amber foot increased dramatically and suddenly all the indications of a stall appeared on the airspeed indicator. The airspeed was below amber; into the red; the PLI (Pitch Level Indication) was red and dropped down and the stick shaker went off. As all this was happening; the Captain had been pitching up through 5 towards 10 degrees ANU (Aircraft Nose Up). Normally; depending upon weight on take you will pitch up to about 20 degrees ANU or a few above for obstacle clearance. Then the flight director will quickly dictate to lower the nose to 15-17 degrees ANU until climb power reduction. The Captain handled the situation well; he stopped increasing pitch and held on at about 10 degrees well through the event which lasted about 20-25 seconds total; but kept climbing to get away from the terrain. Towards the end of the event; maybe the last 7-10 seconds the airspeed limitations (high speed) suddenly decreased and we were showing an overspeed situation. Our actual speed at this point was slightly above 195. Also while this was happening; the FD continued to command a pitch up to the 15-17 ANU; actually commanding to pitch beyond the PLI. Also in the last 7-10 seconds; a LVL 2 SLAT DISAG appeared on the Engine Display. The situation ended at about 1;075 meters in altitude. The stick shaker ceased; airspeed; and PLI indications all returned to normal. I can't recall exactly when we retracted the gear; but we didn't not touch the FLAP/SLAT Selector until after 1075 meters and the incident was over.Passing 100 feet AGL on takeoff we were at approximately 175 knots; suddenly we felt the stick shaker and the airspeed tape began to oscillate rapidly; the airspeed didn't change much; but the amber foot increased dramatically and suddenly all the indications of a stall appeared on the airspeed indicator. The airspeed was below amber; into the red; the PLI was red and dropped down and the stick shaker went off. As all this was happening; the Captain had been pitching up through 5 towards 10 degrees ANU. Normally; depending upon weight on take you will pitch up to about 20 degrees ANU or a few above for obstacle clearance. Then the flight director will quickly dictate to lower the nose to 15-17 degrees ANU until climb power reduction.The cause was due to a failure of aircraft systems. I also asked the Captain a few seconds into the shaker if he would consider going through the boost bar. He said he felt it wasn't necessary since the aircraft was still climbing.Captain had been pitching up through 5 towards 10 degrees ANU. Normally; depending upon weight on take you will pitch up to about 20 degrees ANU or a few above for obstacle clearance. Then the flight director will quickly dictate to lower the nose to 15-17 degrees ANU until climb power reduction. The Captain handled the situation well; he stopped increasing pitch and held on well through the event which lasted about 20-25 seconds total; but kept climbing to get away from the terrain. At the start of the event I called out the Captain's airspeed and told him I was showing the airspeed tape in a stall; even though I suspected it wasn't as visually outside our pitch attitude was normal. I also asked/recommended going through the boost bar. I also called out when I was showing overspeed to compare the foot and speed limit on his side. I was also monitoring the Engine Display throughout for any other indications; which I did see the SLAT DISAG message.Furthermore; I'm aware (verbally from other crews) of this aircraft having this problem going back to mid DATE2. We were scheduled to fly this aircraft but the mechanic told us it was having a low level stall issue and SLAT DISAG issue so it was grounded and we flew a different plane instead. I'm was quite [shaken] up for the remainder of the flight and that such a severe safety issue continues to happen unimpeded with minimal maintenance response other than a swap of individual components and an 'ops check okay RTS (Return To Service).' More oversight of Maintenance Control by the Supervisor is definitely necessary. After such a dangerous problem; it seems that a confidence flight with two LCAs (Line Check Airmen) recreating the same scenario is warranted to confirm the issue; has been fixed properly.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.