EMB-170 flight crew reported unreliable airspeed and pitch attitude indications on the Captain's and First Officer's instruments during initial climb. Flight crew completed an air turn back and landing at departure airport.
Synopsis
EMB-170 flight crew reported unreliable airspeed and pitch attitude indications on the Captain's and First Officer's instruments during initial climb. Flight crew completed an air turn back and landing at departure airport.
Narrative
We were operating flight ABCD ZZZ to ZZZ1. Aircraft X. We arrived at the aircraft on time around XA:50am local time. I pulled the release from my tablet and briefed the crew about today's flight. I did my normal flow and all checklist were performed. I briefed my First Officer on the release and went over the weather in ZZZ and ZZZ1. We then began to load up the FMS. ATIS was received and so was fit for duty and the clearance. We did have a small change in our route but noting that was to effect the flight. We were all loaded up and the flight attendants closed the main cabin door and we were ready for push. Pushing back from the gate was normal and we started up E1. After getting cleared to taxi to Runway XXR I asked my first officer to start E2. Both engine starts were normal. There was also no EICAS messages that were present. We were cleared for takeoff with a left turn to heading of 170 up to 5000 feet.On the takeoff roll Everything was normal from what I saw. We lifted of at rotation speed with no abnormal indications. At 400 feet I called for heading. Reaching 1000 feet I called for VNAV. Upon reaching around 1200 feet indication the aircraft was at the point to call for flaps 1. Shortly after that I noticed that the airspeed begin to rapidly increase and the attitude indication was showing a decent then switched to a climb. At this point I did look at the pitch trim but it was still at the takeoff configuration and I felt not resistance in the controls. I disengage auto throttles and set the aircraft in a level state using outside references and set the N1 to around 80%. The airspeed was still at an increased state around 250 knots indication and the altimeter was showing around 3000 feet on my side. I asked my First Officer if she wasseeing the same indication on her side. She did agree with me that she was also seeing the same. At this point I felt the aircraft was in a stable state and asked my FO to [request priority handling] with ATC and advise them that we were returning to the field. ATC advised a left turn but I noticed that it would take the aircraft into a layer or clouds so I decided to make a right turn. This was a good decision based on being able to have ground references vs taking a left turn into IMC conditions over a dark lake with faulty instrument information on both PFD's and the backup instrument.I was hand flying the aircraft and I did consider the QRH at this point for unreliable airspeed; but various other instruments were also unreliable. We were at a low altitude in night time conditions with the weather quickly moving toward the field; and my goal was to get the aircraft safely on the ground while the field was still in sight. I felt that orbiting to buy us time while reading through the QRH at a very low altitude with inaccurate instrumentation would put the aircraft in an unsafe situation; especially with the weather rolling in. The only two instruments at this point that I felt that were reliable were my radio altimeter and my GPS ground speed indication; which was showing the same information on both PFD's.I asked my First Officer to pull the landing data from the aircraft performance manual based on our current weight. After she pulled the numbers and loaded them up. I asked her to load up the ILS Runway XXR into the box. She was able to get this loaded and I asked for flaps 1. She briefed the approach and we set mins. While she was doing all this I did feel comfortable to contact the FA's via the emergency button. I told them we were returning to the field due to loss of instrument indications. They asked for FOB and souls on board.At this point I asked my FO to advise ATC that we were ready to return to the field and land on Runway XXR. ATC advised us that the MSA in the area was 2800 and that I would have to make turn right to head over the water due to towers at our eleven o'clock area. I proceeded with a light right turn to transition to a left downwind for Runway XXR. During the entire time my RA wasstable around 2700-2800 feet and my ground speed was indicated around 190-220 based on the winds. I asked my FO to enter ice speeds due to the fact I had no reliable information on current airspeed and i wanted to have a safety buffer on landing the aircraft. When I felt that we were in a good state we advised ATC that we were ready for the approach on Runway XXR. At this point I asked my FO for Flaps 2 and started a gradual left turn back to the airport. Indicated ground speed was 170-180 knots. As we approached the LOC course and were approximately 4DME to the final approach fix I asked for flaps 3 and bug 180 on the airspeed. Even though i had my FO bug this unreliable speed it was more for me to have a reference for landing configuration. The RA was showing 2700 feet and the ground speed of 150-160knots. I switched to green needles so I would have that raw data from guidance to land on Runway XXR.Upon reaching the final approach fix I called for gear down. Shortly after that we intercepted the glideslope and I called for flaps 5. I did have the landing lights; and PAPI lights in sight which showed 2 red and 2 white lights. The approach speed was set at 150 but I was using the only reliable information I had presented to me which was my ground speed and my RA. On the final approach for landing I kept an average ground speed of 141 and I was visual outside using the PAPI lights. One thing we both noticed was that around 1500 RA the plane stated minimums from what we had set for this approach but we were no where close to this via the RA indication. At 800 feet I asked my FO to contact the FAs and give them the brace command. I did this as a safety factor. At 500 feet RA the aircraft was in a stable state. At 200 feet RA we crossed the threshold and around 50 feet I began to reduce the power to idle. We landed at the later end of the 1000 foot marker and I brought the aircraft to a stop. EMS was standing by. I stopped on the runway for a moment and tower asked if we need any help. We advised them no help was needed. We taxied off the runway and returned to the gate where the ground crew was waiting for us. During the entire event I found power settings that were keeping the aircraft in a stable state of flight based on the information that was available to me.After running the parking checklist I made an announcement over the PA. I stated we had to return to ZZZ due to faulty instruments; thanked them for their patience and understanding and welcomed them back to ZZZ.After that I immediately called Dispatch and advised them of what had happened. Then I called Person A and advised her on what had just transpired. Shortly after this I was contacted by the on duty pilot. I advised Maintenance about the issues I had with the aircraft and per Person A I advised them that we needed to preserve the data for this flight. I did review the QRH after landing.Added conditions to this event include being dark outside. Being in a fully loaded aircraft that just took off from the airport; clouds layers that were arriving in the terminal area. The need to return to the airport using some type of navigation due to not being able to preform a visual approach at night.My FO did state that on the takeoff roll she noticed that the bugged FMS speed jumped to 80 and back to rotation speed. There weather was 18 degrees C with broken clouds and an overcast layer at 1800 feet reported by ATIS. We never entered IMC conditions and no visible moisture was present.I was aware of the QRH for unreliable airspeed and this was considered and being at a critical state of flight I made a command decision to get the aircraft configured for landing; I had the aircraft in a stable state of flight and we were task saturated. I had weather to the east and a cloud layers above. I made the decision to return to the airport asap that was in night VMC conditions. I used my years of experience in the aircraft; my training provided to me by company; my aircraft systems knowledge and publications provided to us. I stand by all decisions that were made to safety return this aircraft; the passengers and my flight crew to a safe landing in to ZZZ.
Second reporter narrative
On Day I was the First Officer (FO) on flight ABCD from ZZZ to ZZZ1. It was an early show and it was still dark out in ZZZ. I performed a walk around of the plane and everything looked normal. All checklists were performed as normal; and nothing out of the ordinary occurred during ground operations. The Captain was pilot flying during this flight; and I was pilot monitoring. The first abnormal thing I noted was during our takeoff roll; around V1 the airspeed bug jumped down significantly to somewhere near 80 knots; then instantaneously jumped back up (within 1 second). I did not see this as significant enough to warrant a rejected takeoff. Additionally; per the SOP; FOs cannot call 'reject;' and by the time I would have communicated this even to the captain; we would have been well past rotation speed. We rotated as normal; and brought the gear up once a positive rate was established. Passing 400 feet; on the captains call I selected heading; and we turned left to a heading over [the] lake that ATC gave us. Passing 1000 feet I selected VNAV. Upon reaching a safe airspeed; the captain called for flaps 1 and I selected that. When the captain called for flaps up; we were just over the flaps up speed; somewhere near 170 knots. Within seconds the aircraft's indicated speed was in the high 200's; and we received a 'high speed' alert. I was heads down looking at the flap retraction gauge until I heard this alert.During this same time I saw the aircraft pitch down and up erratically. The autopilot was never engaged. The Captain disconnected the auto-throttles. I initially thought the emergency was runaway pitch trim. The Captain was flying; but I grabbed the control column to feel if the trim was running away. The Captain stated 'I have the aircraft' multiple times; so I relinquished controls. I noted that upon feeling the control column; there was no abnormal downward pressure on the yoke; so I was sure it was not runaway pitch trim. During this time the Captain then noted that our instrumentation was displaying inaccurate information; and asked me if my side was showing the same instrumentation as his side. I crosschecked his PFD and the indications appeared the same as mine; so I responded they appeared the same. He told me to tell ATC we were returning to the field immediately; and prompted me to set up the FMS for an arrival back into the airfield. He initially instructed me to set up for a return to Runway XXL; which was opposite direction of where we had taken off. He began a turn toward the right back towards the field to avoid penetrating low weather that was over [the] lake. There was also significant weather above us; so we did not climb up any higher. I was heads down for a few minutes; trying to set up the FMS for an emergency return to Runway XXL. By the time I had gotten an approach to XXL built; we were parallel with the runway; and he instructed me to change the approach and set up for XXR. I built the new approach in the box.I pointed out a few large towers on the horizon. Moments later; ATC advised us of the 2800 foot MSA; referencing the same towers. Per the Captains request; I attained landing speeds from the manual and loaded them into the box. He then instructed me to get ice speeds; which I did. I felt comfortable doing this; noting that with a 10;000 foot long runway we felt safer to fly fast than on the slower side with potentially inaccurate airspeed information. I activated vectors for the approach when he was ready to turn in. The further we got from the field; the more weather there was; so I agree with the decision to turn back to the field; rather than penetrating the weather with instrumentation that was in question. I monitored the approach as my Captain flew it. I noticed significant altitude discrepancies throughout the entire approach; based on distance from the field and the PAPI's. At one point the plane seemed to indicate that we were about 1000 ft. higher than we actually were. Additionally; I noticed the plane called out 'minimums' when the altitude was reading '1500' which is not consistent with the 880 ft. minimums that were set; and TDZE of 672 ft. I crosschecked to ensure the correct altimeter and minimums were set; and they were.The Captain stated that he set a certain N1 that kept us at a safe flying airspeed throughout the duration of the event. I agree with his decision to land the aircraft at the field while we were still in night VMC; rather than holding to run the QRH which did not appear to be all-encompassing to the situation we were experiencing. I believe that if we held to run the QRH; weather would have overtaken the aircraft; putting us in a more dangerous situation. We were already at a low altitude in night time conditions with questionable altitude and airspeed indications; and we were task saturated. The Captain landed the plane normally on Runway XXR. We taxied back to the gate.Going forward; I would recommend a few minor changes to the FO initial training syllabus that I believe would enhance the program overall. I think FO's would benefit from a quick lesson on how to program an emergency return into the FMS. This was not covered during training; and although it may seem intuitive; as a new FO to this aircraft I fumbled with setting up the box which kept me heads down for a significant portion of our flight. Second; I think we should consider allowing FOs to call rejected takeoffs. I believe it is a safety hazard to not allow a qualified pilot to be able to call a rejected takeoff.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.