B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Total 20000; Flight Crew Type 8815
Aircraft Equipment Problem Critical
Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition
Weather; Manuals; Aircraft
Refer to prior [safety] reports. The conclusions of both [reports] were not reviewed as POSSIBLY being related. Both [incidents] were identical except for the airspeed too low and overspeed warnings which were experienced as well as all other items mentioned.  All three AIRSPEED and ALTIMETERS were INOPERATIVE in both cases. The [incidents] occurred in two different airplanes. The most recent occurred in night/IMC conditions with heavy thunderstorms at cruise; descent and approach. Ground based ATC radar was used to readout our altitude and groundspeed. We were unable to fly the GPS approach in use due to loss of VNAV. We used the opposing runway with raw data ILS on standby system with 20-30 knot tailwinds on a wet runway. The onboard [checklist] is in total error regarding the pitch and power settings. The QRH (Quick Reference Handbook) references were accurate using the standby attitude indicator. Also the Captain's iPad froze and the onboard paper QRH was used. First Officer was manually flying the aircraft.
B737 Captain reported two possibly related instances in two different aircraft involving loss of altimeters; airspeed; and VNAV.