Narrative:

Line check airman (lca) in left seat; oe first officer (first officer) in right seat; new lca observing in one jumpseat and 757 first officer student on pleasure travel in the other jumpseat. During the takeoff roll on 25R lax; the first officer and I began to get a gradual increase in static through our headsets. After liftoff; the static turned to a full blown loud squeal which disabled both captain and first officer communication with ATC. I instructed the first officer to just continue to fly the aircraft and comply with the departure.we completed the after takeoff checklist and engaged the autopilot. By this time the observing lca and other jumpseater realized that we were having difficulty communicating with ATC and began to help trouble shoot the problem. We leveled off at 5;000 feet and 250 KTS and complied with the routing. A slight left deviation was needed for a build up at twelve o clock. We made several attempts to establish communication by selecting different mikes; headset plugs; etc. To no avail. I set the transponder to 7600 and began reading the SID lost communication procedure aloud when the lca observing said he was able to hear and talk to ATC on the observer audio sel panel.once ATC communication was reestablished; we continued climbing and assessed the situation. I plugged my headset into the observer panel and used the hand mic which worked well. Once above 10;000 feet; I discussed the situation with the rest of the crew as we continued to trouble shoot the problem. All radio functions were normal using the observer panel and the decision was made to continue for the time being. Dispatch and maintenance control were consulted and a discussion ensued about whether or not to pull and reset any radio circuit breakers. We chose not to because all radio functions were normal with that panel. We didn't want to lose what we had. The decision was made to continue to destination. As the flight progressed; the first officer noticed the squeal seemed to be isolated to the interphone system and as long as we didn't use that part of the panel the radios were useable. We proceeded and eventually diverted for weather and sent a logbook entry concerning the issue and coordinated this with dispatch and maintenance control prior to departure. The lca in the jumpseat was paramount in the successful outcome of this event. Being able to reestablish ATC communication in a timely manner on the observer panel was key.

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Original NASA ASRS Text

Title: A B757 flight crew and a pilot on the jump seat described a lost communications situation that developed during the takeoff from Runway 25R at LAX. A loud squeal was heard in both pilots headsets and over the speaker making ATC inaudible. Eventually ATC is contacted using observer audio panels without the squeal. Troubleshooting indicated that the squeal may have been coming from the interphone system.

Narrative: Line Check Airman (LCA) in left seat; OE First Officer (FO) in right seat; new LCA observing in one jumpseat and 757 FO student on pleasure travel in the other jumpseat. During the takeoff roll on 25R LAX; the FO and I began to get a gradual increase in static through our headsets. After liftoff; the static turned to a full blown loud squeal which disabled both Captain and FO communication with ATC. I instructed the FO to just continue to fly the aircraft and comply with the departure.We completed the after takeoff checklist and engaged the autopilot. By this time the observing LCA and other jumpseater realized that we were having difficulty communicating with ATC and began to help trouble shoot the problem. We leveled off at 5;000 feet and 250 KTS and complied with the routing. A slight left deviation was needed for a build up at twelve o clock. We made several attempts to establish communication by selecting different mikes; headset plugs; etc. to no avail. I set the transponder to 7600 and began reading the SID lost communication procedure aloud when the LCA observing said he was able to hear and talk to ATC on the observer audio sel panel.Once ATC communication was reestablished; we continued climbing and assessed the situation. I plugged my headset into the observer panel and used the hand mic which worked well. Once above 10;000 feet; I discussed the situation with the rest of the crew as we continued to trouble shoot the problem. All radio functions were normal using the observer panel and the decision was made to continue for the time being. Dispatch and Maintenance Control were consulted and a discussion ensued about whether or not to pull and reset any radio circuit breakers. We chose not to because all radio functions were normal with that panel. We didn't want to lose what we had. The decision was made to continue to destination. As the flight progressed; the FO noticed the squeal seemed to be isolated to the interphone system and as long as we didn't use that part of the panel the radios were useable. We proceeded and eventually diverted for weather and sent a logbook entry concerning the issue and coordinated this with Dispatch and Maintenance Control prior to departure. The LCA in the jumpseat was paramount in the successful outcome of this event. Being able to reestablish ATC communication in a timely manner on the observer panel was key.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.