B757-300 flight crew reported an air turn back was caused by a pitot system obstruction. The flight crew made a precautionary landing at destination airport.
Synopsis
B757-300 flight crew reported an air turn back was caused by a pitot system obstruction. The flight crew made a precautionary landing at destination airport.
Narrative
During takeoff roll; First Officer (FO) as PF (Pilot Flying); airspeed did not seem to be accelerating normally; but it was subtle. As we approached the call out for 100 knots; it became apparent that the Captain's airspeed indicators (analog and digital tape) were substantially lagging behind the FO's and the standby instruments. Just after the Captain's airspeed read 100 knots; the actual airspeed was nearly at V1. We continued the takeoff because we were already in the high-speed regime. Shortly after liftoff; there was an IAS Disagree EICAS (Engine Indicating and Crew Alerting System) message and caution. We applied the Immediate Action steps and consulted the QRC (hard card). I then went into my iPad Electronic Flight Manual for the rest of the checklist items. The highest difference noted between the Captain's airspeed and the standby and FO's airspeed was approximately 60 knots.I assigned the FO to take the radios and continue to fly while I ran thru the checklist. We informed ATC of our problem and asked to stay in the local area to troubleshoot. We were sent to the ZZZZZ intersection and told to hold as published at 3;000 feet. We asked for 10 NM legs in the holding pattern and were given clearance for that request. We later asked for a higher altitude for a margin of safety and were assigned 7;000 feet.I then sent a message to Dispatch to call me and subsequently received a message to call AIRINC for Company phone patch. I spoke to Dispatch (NAME) and asked him to get Maintenance Control on the line; which he did. Throughout this phone patch; communication was very difficult. It seemed that all three of us were having difficulty hearing each other at times; and I was not always sure who was talking or if anyone was hearing me.We made several turns in holding as we waited for inputs from Maintenance Control and for Dispatch to work out the numbers for a possible overweight landing back in ZZZ. Dispatch first sent us landing weights for Flaps 30 on Runway XXL; which was not the active runway. Then he sent data for Flaps 30 to RWY YYL. I informed him that we needed Flaps 20 data due to the directives in the IAS Disagree procedure; so he sent me data for Flaps 25. At that point I gave up on the communication about the flaps and landing data because we had consulted the Abnormal Configuration chart in the Flight Manual and we had plenty of margin available under the conditions for RWY YYL. Maintenance Control asked to be let off the call after we made the decision to return to ZZZ. Once we were all in agreement about making the return to ZZZ; Dispatch asked on a couple of occasions if we were planning to request priority handling. I said I would be; once we were ready to return. After confirming all items in the FM procedure were addressed and we obtained ATIS information and briefed the approach; we requested vectors out of holding and for the diversion back to ZZZ. I also received priority handling and gave ATC the requested information regarding fuel remaining; souls on board; and the nature of the problem.We received vectors to return and informed ATC about our higher-than-normal approach speed; since the procedure required a Flaps 20 approach. We flew the visual approach to RWY YYL and landed without incident. Touch down was smooth and well within the touchdown zone. We cleared the runway and saw emergency vehicles heading our way; so I stopped momentarily on the taxiway. ATC asked if we wanted to cancel the priority. I looked at the brake temperatures and they looked okay; so we cancelled the priority handling and taxied without incident to Gate X. The Brake Temp light did come on at the gate for a few minutes; but we had already let operations know about it before anyone approached the airplane. The brakes cooled down seemingly quickly thereafter. A write up was made and a few representatives from operations came to the aircraft to ask more questions about what had happened. We did not take that airplane to ZZZ1 that day; but did see in the maintenance document the next day that there was an obstruction found in the pitot static system after our returned flight the previous day.
Second reporter narrative
During my exterior pre-flight inspection no abnormalities were noticed with any pitot tubes or areas surrounding them. I was PF (Pilot Flying) for this flight. Takeoff roll and acceleration felt normal on Runway YYR. As we were accelerating down the runway I did not hear the Captain say the 100 knot call. My first thought was maybe he said it quietly and I missed it. At that time; I felt we may be accelerating through 100 knots so I looked down and saw we were at approximately 120 knots. I looked back down at my airspeed a couple seconds later and we were closely approaching V1 and about that time he called 100 knots. My visual cues and experience with the airplane; told me that was not 100 knots and I said 'V1; rotate' referencing my airspeed indications. Rotation felt normal. Aircraft control authority and pitch felt consistent with the speeds I was seeing on my airspeed indicator. We raised the gear; turned southeast to our cleared heading of 155 degrees. EICAS (Engine Indicating and Crew Alerting System) CAUTION message 'IAS DISAGREE' appeared. At 800 feet we reduced thrust; raised the flaps up from 15 to 5 climbed out at about 200 knots to 3;000 feet. Departure was contacted and the captain informed them of the nature our IAS issue. We were cleared to hold over ZZZZZ as we worked through the non-normal QRC Immediate Action Items & QRH. We climbed up from 3;000 feet to 7;000 feet while flying at 205 knots and flaps 5. While running the QRH we came to the conclusion that the left side air data was corrupt. The standby airspeed and right side airspeed agreed as well as additional information from ground speed. We held for about 30 minutes in total while we worked the situation; completed the non-normal procedures; made our plan and communicated with Dispatch; Maintenance Control and FAs (Flight Attendants) and customers. The Captain used the 'CALL ME' function on ACARS to make a patch with Dispatch. Dispatch replied back with HF frequencies which seemed odd to us. The communication was difficult using HF as the 757-300 does not have SATCOM installed. We were not sure why dispatch did not give us a VHF frequency as we were close to land and certainly within range of VHF. We did not think in the moment to request a VHF patch because we were busy and had already started down a path using HF. We asked Dispatch and Maintenance Control about overweight landings and getting numbers for that. At first Dispatch sent us numbers for XXL and using Flaps 25. This could have been in error; we are not really sure. Ultimately we agreed on an overweight landing using the non-normal configuration landing distance calculations from the QRH 757-300 tables. We agreed that the Captain would take over and be PF for the visual approach and landing. We requested priority handling before we headed back to the airport as to have CFR (Crash Fire Rescue) on standby. A normal approach and landing using Flaps 20 was conducted. We taxied to the gate and deplaned.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.