Date: 202008
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Aircraft component: Airspeed Indicator
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Distraction
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Other Post Flight
Result: General None Reported / Taken
Contributing factors: Aircraft; Environment - Non Weather Related; Human Factors
Primary problem: Human Factors

Narrative: Ground operations were relatively uneventful except for some discrepancies with the aircraft upon arrival.  APU was running and ground power was on the aircraft; there was 300 pounds of fuel in the center tank and there was a 400 pounds split in the mains with the left side lower.  I discussed with the FO our cost saving measures which require waiting to start the APU.  I elected to run the APU off of a right main with cross feed open in order to balance fuel prior to takeoff.  Our release was scheduled for 10;500 pounds but we had 12;000 pounds in the tanks and was surprised the release was not accurate.  The FO and I discussed TO and Landing data; fuel distribution; and the location of center body fuel pumps as well as the requirement to monitor the cockpit if center pumps are used. We also discussed the need to be extra vigilant when flying into or out of ZZZ or ZZZ1 due to maintenance and storage at those locations.  Forms review revealed [seats] X 1; 2; 3 power ports inoperative and I requested the gate agent re-seat the passengers from X1 AND X2 prior to boarding.  FO did the walk around about 20-15 minutes prior to departure.  On return I asked if he saw the pumps in the wheel well; since no one had shown them to him; we went out quickly and I pointed 4 fuel pumps accessed from the wheel well.  The rest of ground operations appeared uneventful.  We pushed back 5 minutes early with no abnormal last chance from the ground crew and then we were give a controlled TO time due to flow control into ZZZ2.We were cleared for Takeoff and as PF I hand flew the aircraft to approximately 12-15;000 feet and then engaged the left autopilot.  After level off we were cleared direct ZZZZZ (feeder fix for ZZZZZ ZZZ2).  During cruise @ FL220 I burned the 300 pounds from center tank and cross fed to balance mains.  At approximately 20 minutes after TO; while in cruise I notice the CA and FO altimeters were 'bouncing' about 20 feet standby was normal and all 3 airspeed indicators agreed.  We discussed possible mountain wave; or some static port icing. Airspeed was stable but we set 280 KIAS then we set 290 KIAS for STAR transition.  Then we were cleared ZZZZZ and I set 270 KIAS to match STAR restriction. Then 20 miles prior to top of descent we were given 'descend via ZZZZZ4'.  I set 6000 feet in the MCP and verified VNAV path and executed the 'descend now' for 1000 VVI to capture the path.  Then CA and FO altimeters were about 20 feet different and they were about 250-300 feet from the standby altimeter. During the descent we were given 17;000 then stopped at 11;000 feet then direct ZZZZZ for XXL then Descend and maintain 5;000 feet.During the descent; the split from standby altimeter was reduced and the bounce seemed to quicken and lessen.  By 7;000 feet it had disappeared completely.  All indications were normal.  We configured Flaps 30 degrees Brakes 2 with a standard landing assessment.  I disengaged the autopilot at about 1;000 feet and the landing rollout and taxi back to X22 were uneventful.I had failed to sign the logbook prior to flight. So; after flight I reviewed the last 7-10 days to see if there were any similar write-ups.  I saw the aircraft sat for 3 days.  I didn't notice anything else in the logbook and signed it.I met the oncoming CA on the jet bridge and discussed what I saw.  I offered to write it in the logbook if he wanted and he declined.  I said it was a little weird but seemed to self correct and didn't want to waste Maintenance time on something that they 'could not duplicate.'  Later I received a call from a safety representative and was told about an air return for an unreliable airspeed / altitude.  We agreed I should have written up the event in the log book and this is the reason for my report.Causal factors include:1: Maintenance procedure not complied with or annotated in logbook.2: Aircraft repositioning crew failed to notice static blockage.3: Inattention to detail. Flight crewfailed to notice static blockage during walk around.4: Low sun angle and Jet bridge may have partially obscure view of blockage.5: Ground push crew failed to notice blockage during ground operation.6: Arrival ground crew failed to notice blockage.7: PIC failed to make a logbook entry regarding altitude anomalies even though they appeared to self correct.8: Ground/Maintenance failed to notice blockage and PIC did not do a post flight inspection after having knowledge of the possible problem with the static ports.Suggestions:1: Write up any abnormal indications and let maintenance determine if it's acceptable or not.2: Be extra vigilant because airplanes are being stored and they break more often.3: ZZZ is a maintenance base; so consider an early show and have both pilots do the walk around.4: Focus!  Many FOs are distracted with job security.5: PIC post flight. Take the extra minute to do a post flight walk around after an event like this or one requiring a write-up.




Synopsis: Air carrier Captain reported experiencing unreliable airspeed and altitude indications. Captain stated that due to not reviewing the logbook before the flight and an improper preflight; the potential pitot-static system issue was not identified prior to the flight.