B737 Undifferentiated or Other Model
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Flight Crew Last 90 Days 139; Flight Crew Total 4607; Flight Crew Type 4607
Communication Breakdown; Human-Machine Interface; Confusion; Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation - Speed All Types; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Provided Assistance; Flight Crew Overcame Equipment Problem; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Departure Airport; General Flight Cancelled / Delayed; General Maintenance Action
Aircraft; Human Factors; Procedure
Flight XXXX scheduled as an empty ferry flight ZZZZ-ZZZ diverted into ZZZZ after an Airspeed Disagree on takeoff.This pairing was originally built as a day trip deadhead to ZZZZ; fly to ZZZ. After determining that the appropriate parts had not yet been sent to ZZZZ; we were reassigned to a two day with two short rest overnights. This created a fatigue management threat. I slept well after my day trip ; slept virtually the entire flight down and multiple hours in the afternoon. Though my sleep was separated into multiple longer segments; I felt rested for the flight.In this narrative; I am the Pilot Flying until after exiting the hold and commencing the approach. On the van drive in; we discussed the paperwork and determined a plan of action to account for the ferry flight aspect. Having reviewed the FM; the Captain would do the walk around; while I set up the flight deck and completed the cabin portion of the ferry prep checklist (minus the arming of 1L/1R). He would then do a walk through to double check my work. Flight deck setup was straight forward; I had just been to ZZZZ so setup; ATC procedures; and expected clearance/taxi routings were familiar. On our first takeoff; at about 60 kts.; an ENG master caution came on. Captain's diagnostic time resulted in a reject being performed at 70-80 kts. Tower was advised; and we back taxied to clear at Taxiway XX in anticipation of being able to resolve the dual EEC ALTN mode indications and try again.  After a Maintenance Control phone patch; MEL 73-XX-X was applied. A check of the bite test was initiated; but terminated once Maintenance Control was made aware of the 5% N1 on both engines precluded that test. An APU restart with dual engine shutdown was not attempted. Two threats were added: auto throttle off takeoff and max thrust required on an empty plane.  New takeoff data was up linked and takeoff roll commenced.  From my habit pattern; I tend to glance down in response to the 100 kts. call to see if there was anything glaringly obvious on the PFD (Primary Flight Display). I saw and announced airspeed disagree annunciation. The Captain was able to determine that the likely culprit was my indication with two working indications remaining. He announced 'continue.' Shortly after v1 was announced.  Without time to verbalize the thought; I anticipated a higher than usual pitch attitude would be necessary to account for the max thrust/empty jet combination. Aircraft was rotated and brought to higher than normal; but appropriate for conditions; attitude. My flight director indicated a descent to recover from the low IAS. This was ignored. The Captain verbalized his logic process about which IAS indications were valid. A glance over showed IAS stable in the 180-190 range.Ergo; we could fly the aircraft with the remaining valid indication and entered stabilized cruise at 6;000 ft.; clean and about 240 kts. I agree with the Captain's assessment made around this time that there were sufficient added threats present that an underweight air return to a field in VFR conditions was prudent compared to continuing on into class 2; non RVSM; with multiple malfunctions. An air return was requested and a clearance direct ZZZZZ for the RNAV XX with a sub clearance to hold as published over ZZZZZ until checklist completion. The Captain completed the airspeed unreliable; which allowed autopilot on holding. Cruise altitude was reset on the pressurization panel and the cruise page to facilitate an RNAV path for a visual approach with LNAV/VNAV backup on the Captain's PFD. The approach was setup and briefed; and; after the descent checklist; we exited the hold to start the approach. At this point; I suggested that the Captain fly the approach since he had more readily accessible data directly in front of him than I did. We transferred controls; and he landed the aircraft. On descent; we got a VNAV disconnect; but a PAPI in sight continuation / v/s descent was considered safe.The FO (First Officer) airspeed indication was in the low speed awareness tape while CA (Captain) side was between ref +5 and stabilized criteria. The FO side stick shaker activated accordingly. After landing deceleration; below 100 kts.; the failed IAS started to converge with the working displays. Around 70 kts.; the airspeed disagree dropped off; and; by taxi speed; all indications were again equal. My assessment is that we had a near; but not total blockage of the FO side pitot tube.Return to gate normal; shutdown and parking checklist normal. ELB entry made. Termination accomplished.  For unrelated reasons; I needed to contact the Maintenance personnel on site; and he indicated that burnt bodies of flying insects (possibly bees) had blocked the tube. They were also the reason that the prior rejected takeoff happened; but since the ENG master caution was primary and the speeds matched at low speed; neither of us saw the airspeed disagree on the first attempt. This would have been caught if the above mentioned APU start and shutdown and been accomplished.
My report is based on Aircraft X; a ferry flight ZZZZ-ZZZ. This flight had multiple issues and threats that need to be addressed. The aircraft; a B737-900 was parked for a number of days in ZZZZ waiting to be repaired (L1 window replacement) before this flight was attempted after the repair was completed and a new maintenance release was issued. After receiving / reviewing (with a separate phone call to Maintenance Control to confirm the repair); I accepted the Dispatch release. The Copilot and I divided our duties to prepare the aircraft to depart to ZZZ for a late night oceanic ferry flight. Our first issue came up after starting the engines and BOTH ECCs went into alternate mode. Maintenance Control was contacted via phone and a cycling of the ECCs button cleared the alternate mode and back to normal operation.The first attempt to depart ZZZZ resulted in a low speed (70-80 kts.) RTO (Rejected Takeoff) due to BOTH ECCs going into alternate mode with a Master Caution light- ENG annunciation. The RTO was performed and with all associated checklists completed; Maintenance Control was again contacted while safely parked off the runway . Maintenance Control wanted to perform a 'bite' test on the ECCs but this required the engines to be shutdown (I did not know this and would have possibly shown more issues) but instead stated we will just MEL the ECCs which created more of a threat to the flight crew. After a review of the MEL and flight crew duties ( i.e. no auto throttles for Takeoff) a second takeoff was initiated.A full power takeoff (manual setting) was started with V speeds V1 116k Vr 133 V2 144. The First Officer (FO) was performing the takeoff. Shortly after V1; I heard the FO state airspeed disagree alert. My attention was split between my airspeed indicator and the Center display for engine thrust. From previous training years ago; a scan of my airspeed indication; the standby's and the FO's I realize I had the proper information compared to the standby airspeed display and announced to 'continue' to the FO. I then announce to the FO; I had the proper airspeed Indication and approaching Vr I called ' rotate '. The FO started a normal rotation and pitched up to approximately 12 degrees while I was stating current airspeed. Within 10 seconds; the FO airspeed indication appeared to be normal and the airspeed disagree alert went away. I thought this was a momentary glitch as we continued the climb but unfortunately the same airspeed disagree indication returned in less than one minute. I informed the ZZZZ Tower that we had an airspeed indication issue and requested to maintain current heading (020 degrees) away from any terrain and level off at 6000 ft. This was granted by the ZZZZ Tower and then we switched to the Local Approach Authority for further instructions. We then reviewed the immediate action items for airspeed unreliable with the First Officer manually flying; auto throttles off using the Captains airspeed indication as reliable airspeed indication. I then requested from the Approach authority to enter a hold (ZZZZZ) near the initial approach phase for Runway XX so we could review the QRH prior to returning ZZZZ. The airspeed unreliable expanded QRH checklist gave us the option to continue the flight with a reliable airspeed indication but considering the previous RTO earlier and our flight plan entering class II airspace; I elected to return back to ZZZZ for a visual approach in VMC weather. After entering the hold at ZZZZZ and finishing the QRH checklist; we sent an ACARS message to Dispatch advising them diverting back into ZZZZ. The FO and I discussed the type of an approach back into ZZZZ and confirmed the checklists needed to complete the arrival back into the airport. The A autopilot was used during the hold and the initial approach phase. We attempted to use VNAV during the approach but the descent data did not properly lineup and we use the PAPI information and raw data back up (3 to 1) to complete the landing. I flew and landed the aircraft with my flight Director giving more appropriate pinch commands than the FO. The aircraft was configured earlier than normal as prescribed from the QRH and the FO's stick shaker began to activate as the aircraft slow to the target speed. The FO's incorrect airspeed indication was approximately 25-30 kts. slower than the CA and standby airspeed indication. We landed with normal flap configuration (30) using the auto brakes and turned off the runway. The ZZZZ Tower then asked us if we needed any further assistance and we said no and continue to taxi back to the ramp where we first started earlier that evening. The FO noted to me after we were slowing and exiting the runway the airspeed disagreed light went away.After parking the aircraft; we contacted Dispatch and had a discussion with them along with Maintenance Control.  Maintenance Control advised us that the possible cause was bugs infiltration into the pitot static system.
B737-900 flight crew reported pitot/static systems problems caused a rejected takeoff and an air turn back. Flight Crew reported insects had blocked the First Officer's pitot tube.