IF either the helicopter or the plane that crashed together had an altimeter not working properly this could have caused the crash

If I remember correctly, altimeters are based upon the air pressure at different altitudes. If that is still true in the Passenger jet or the Helicopter, what if the air pressure was unusual yesterday and gave an incorrect reading? Though Helicopters and planes have done this dance for years and years somehow something went wrong this time while the passenger plane was trying to land at a secondary landing site called Runway 33 at Reagan National Airport. What I'm saying is this could have been an altimeter not functioning right in either the passenger jet or the Helicopter because usually they are missing each other by only about 200 feet vertically to begin with during these near misses that have been going on for years and years at this point.