Narrative:

Flight departed planned the transit of the addis abeba (haaa) [and] khartoum (hsss) flight information regions (firs). While transiting addis abeba at FL380 the flight was in contact with 'addis' on VHF1 125.1 and monitoring VHF2 121.5. Approaching waypoint nideg; 'addis' cleared the flight to 'proceed to labla'. Proceeding direct to labla; the crew observed thunderstorm cells with tops above FL400 to the north in the vicinity of subsequent waypoints bdr and amudo. After the pilot flying (PF) and pilot monitoring (pm) discussed the threat; the pm advised 'addis' of the need to deviate further north to avoid the storm cells and requested clearance direct to waypoint alrap on the fir boundary with khartoum. 'Addis' replied 'unable; proceed direct bdr.' while proceeding direct bdr it became apparent that further deviation to the right was required; and the pm attempted to contact 'addis' to request the further deviation. However attempts to contact 'addis' were unsuccessful at this time; and the pm had to exercise emergency authority to have the PF deviate further right as necessary to avoid the storm cells. After clearing the cells; contact was re-established with 'addis' and the pm advised them of the necessary deviation. 'Addis' subsequently cleared the flight 'direct to alrap.' around this time the PF requested the relief first officer (rfo) relieve him so he could 'take a break in the back for a while'; and the rfo assumed PF duties. Prior to alrap the pm attempted to contact 'khartoum center' on VHF2 125.7 which is the primary contact frequency published in the high enroute chart fir communications information. Unable to establish contact; the pm made an in-the-blind broadcast with the relevant estimated time over (eto) and crossing flight level information. Since khartoum fir is within the area of applicability in-flight broadcast procedures (ifbp); the pm then tuned VHF2 to 126.9 to begin a listening watch in accordance with (in accordance with) with ifbp procedures; and made the requisite 10 minute fir crossing broadcast transmission on the frequency. Additional attempts to contact 'khartoum' on VHF1 using both the primary (125.7) and secondary (125.3) frequencies were unsuccessful. VHF1 was retuned to 125.1; and since the [flight plan] had the flight crossing alrap at FL400; the pm attempted to contact 'addis' with a request to climb to FL400 and also inquire if they had a different frequency for 'khartoum'. However; the pm was unable to make contact with 'addis' before reaching alrap so an advisory transmission was made in the blind that the flight 'was changing to 'khartoum''. Entering the khartoum fir the pm made an ifbp broadcast position report transmission; and again attempted to contact 'khartoum' on primary and secondary frequencies with no success. At this time the flight heard an ifbp broadcast transmission from a flight at a position to the north transiting toward alrap at FL380 in the opposite direction. The PF and pm discussed this potential co-altitude flight conflict and determined the flight should climb to FL400 soon. Another attempt was unsuccessfully made to contact 'khartoum' on VHF1 with the published tertiary frequency 127.3. After visually clearing their flight path and seeing no 'skin paints' on the weather radar the pm exercised emergency authority and directed the PF to climb the aircraft to FL400. The pm made an ifbp broadcast transmission advising 'all stations' of the flight level change; and reattempted to contact 'khartoum' on the primary frequency without success. An in-the-blind transmission advising 'khartoum' of the level change was made on VHF1 125.7. Focused on clearing their flight path during the climb; the pm delayed further attempts to establish contact with 'khartoum' until reaching FL400. When level; the pm opted to attempt contact with khartoum fis on HF frequency 11300 which proved to be successful; and a position report with the level change and VHF contact problemwas conveyed. Khartoum fis directed the flight to contact 'khartoum' on 127.5 which happened to be the last published VHF frequency. Now approaching waypoint gidar contact was established with 'khartoum' on VHF1 127.5 and the controller stated that he had 'been attempting contact on VHF 127.5 several times' and had 'also tried 121.5 with no answer'. The pm apologized for the situation and explained that the flight had been attempting contact on different frequencies and had climbed to avoid a potential conflict. 'Khartoum' made no further comment and cleared the flight to 'proceed to mipol and descend to FL390'. The remainder of the flight was uneventful.multiple factors worked together to create the situations that resulted in the captain's (pm) exercise of emergency authority on this flight: 1) our experience with operations in khartoum and addis abeba firs is new and limited. This was the first time for any of the crew members on this flight. 2) regional VHF radio communication limitations. The ifbp [procedures state] in africa indian ocean region (afi): 'in many firs in the afi region communications both fixed and mobile have either not been implemented or operate well below the required reliability. This has an impact on the proper provision of air traffic services; especially flight information service. Consequently; the afi [region] has decided that the in-flight broadcast procedure (ifbp) should be used within the designated firs in the region as an interim measure until such time as communications facilities affecting the firs in question have been improved.' since ifbp applies to khartoum; our flight was required in accordance with procedure to monitor VHF2 126.9 instead of 121.5 while transiting the fir. Khartoum attempted to use 121.5 to contact us; but we were not monitoring the frequency.3) intermittent VHF contact with addis abeba necessitated uncoordinated weather deviations and impacted subsequent contact with khartoum center. 4) khartoum center was using a VHF frequency that was different from the primary or secondary frequencies available to the crew in the published high enroute chart; and that information was not available to the crew. 5) human error / fatigue may have played a part with the pm not thinking to attempt contact with 'khartoum' on VHF 121.5 after initial failures on published frequencies. He may have been too focused on making contact on published primary and secondary VHF frequencies while maintaining ifbp listening watch. In addition he could have made a query of other flights on the ifbp frequency to ascertain the active 'khartoum' frequency.Suggestions1) update enroute sections of applicable airport briefing guides to address the potential for VHF communication problems to include the potential ramifications of maintaining the ifbp listening watch on VFH2 in lieu of monitoring 121.5. 2) if it can be determined that khartoum is now using 127.5 as their primary frequency; the high enroute chart communications information needs to be updated.

Google
 

Original NASA ASRS Text

Title: An air carrier crew at FL380 transiting the HAAA and HSSS FIR's attempted radio contact for a weather avoidance clearance but were unable. The Captain then deviated and climbed to avoid a nearby aircraft before re-establishing ATC communications. An incorrect enroute chart frequency listing contributed to errors.

Narrative: Flight departed planned the transit of the Addis Abeba (HAAA) [and] Khartoum (HSSS) Flight Information Regions (FIRs). While transiting Addis Abeba at FL380 the flight was in contact with 'Addis' on VHF1 125.1 and monitoring VHF2 121.5. Approaching waypoint NIDEG; 'Addis' cleared the flight to 'proceed to LABLA'. Proceeding direct to LABLA; the crew observed thunderstorm cells with tops above FL400 to the north in the vicinity of subsequent waypoints BDR and AMUDO. After the Pilot Flying (PF) and Pilot Monitoring (PM) discussed the threat; the PM advised 'Addis' of the need to deviate further north to avoid the storm cells and requested clearance direct to waypoint ALRAP on the FIR boundary with Khartoum. 'Addis' replied 'unable; proceed direct BDR.' While proceeding direct BDR it became apparent that further deviation to the right was required; and the PM attempted to contact 'Addis' to request the further deviation. However attempts to contact 'Addis' were unsuccessful at this time; and the PM had to exercise Emergency Authority to have the PF deviate further right as necessary to avoid the storm cells. After clearing the cells; contact was re-established with 'Addis' and the PM advised them of the necessary deviation. 'Addis' subsequently cleared the flight 'direct to ALRAP.' Around this time the PF requested the Relief First Officer (RFO) relieve him so he could 'take a break in the back for a while'; and the RFO assumed PF duties. Prior to ALRAP the PM attempted to contact 'Khartoum Center' on VHF2 125.7 which is the Primary contact frequency published in the High Enroute chart FIR Communications information. Unable to establish contact; the PM made an in-the-blind broadcast with the relevant Estimated Time Over (ETO) and crossing Flight Level information. Since Khartoum FIR is within the Area of Applicability In-flight Broadcast Procedures (IFBP); the PM then tuned VHF2 to 126.9 to begin a Listening Watch In Accordance With (IAW) with IFBP procedures; and made the requisite 10 minute FIR crossing Broadcast transmission on the frequency. Additional attempts to contact 'Khartoum' on VHF1 using both the Primary (125.7) and Secondary (125.3) frequencies were unsuccessful. VHF1 was retuned to 125.1; and since the [Flight Plan] had the flight crossing ALRAP at FL400; the PM attempted to contact 'Addis' with a request to climb to FL400 and also inquire if they had a different frequency for 'Khartoum'. However; the PM was unable to make contact with 'Addis' before reaching ALRAP so an advisory transmission was made in the blind that the flight 'was changing to 'Khartoum''. Entering the Khartoum FIR the PM made an IFBP Broadcast position report transmission; and again attempted to contact 'Khartoum' on Primary and Secondary frequencies with no success. At this time the flight heard an IFBP Broadcast transmission from a flight at a position to the north transiting toward ALRAP at FL380 in the opposite direction. The PF and PM discussed this potential co-altitude flight conflict and determined the flight should climb to FL400 soon. Another attempt was unsuccessfully made to contact 'Khartoum' on VHF1 with the published tertiary frequency 127.3. After visually clearing their flight path and seeing no 'skin paints' on the weather radar the PM exercised Emergency Authority and directed the PF to climb the aircraft to FL400. The PM made an IFBP Broadcast transmission advising 'all stations' of the flight level change; and reattempted to contact 'Khartoum' on the Primary frequency without success. An in-the-blind transmission advising 'Khartoum' of the level change was made on VHF1 125.7. Focused on clearing their flight path during the climb; the PM delayed further attempts to establish contact with 'Khartoum' until reaching FL400. When level; the PM opted to attempt contact with Khartoum FIS on HF frequency 11300 which proved to be successful; and a position report with the level change and VHF contact problemwas conveyed. Khartoum FIS directed the flight to contact 'Khartoum' on 127.5 which happened to be the last published VHF frequency. Now approaching waypoint GIDAR contact was established with 'Khartoum' on VHF1 127.5 and the controller stated that he had 'been attempting contact on VHF 127.5 several times' and had 'also tried 121.5 with no answer'. The PM apologized for the situation and explained that the flight had been attempting contact on different frequencies and had climbed to avoid a potential conflict. 'Khartoum' made no further comment and cleared the flight to 'proceed to MIPOL and descend to FL390'. The remainder of the flight was uneventful.Multiple factors worked together to create the situations that resulted in the Captain's (PM) exercise of Emergency Authority on this flight: 1) Our experience with operations in Khartoum and Addis Abeba FIRs is new and limited. This was the first time for any of the crew members on this flight. 2) Regional VHF radio communication limitations. The IFBP [procedures state] in Africa Indian Ocean Region (AFI): 'In many FIRs in the AFI Region communications both fixed and mobile have either not been implemented or operate well below the required reliability. This has an impact on the proper provision of Air Traffic Services; especially flight information service. Consequently; the AFI [region] has decided that the In-Flight Broadcast Procedure (IFBP) should be used within the designated FIRs in the Region as an interim measure until such time as communications facilities affecting the FIRs in question have been improved.' Since IFBP applies to Khartoum; our flight was required IAW procedure to monitor VHF2 126.9 instead of 121.5 while transiting the FIR. Khartoum attempted to use 121.5 to contact us; but we were not monitoring the frequency.3) Intermittent VHF contact with Addis Abeba necessitated uncoordinated weather deviations and impacted subsequent contact with Khartoum Center. 4) Khartoum Center was using a VHF frequency that was different from the Primary or Secondary frequencies available to the crew in the published High Enroute chart; and that information was not available to the crew. 5) Human Error / Fatigue may have played a part with the PM not thinking to attempt contact with 'Khartoum' on VHF 121.5 after initial failures on published frequencies. He may have been too focused on making contact on published Primary and Secondary VHF frequencies while maintaining IFBP Listening Watch. In addition he could have made a query of other flights on the IFBP frequency to ascertain the active 'Khartoum' frequency.Suggestions1) Update Enroute sections of applicable Airport Briefing Guides to address the potential for VHF communication problems to include the potential ramifications of maintaining the IFBP Listening Watch on VFH2 in lieu of monitoring 121.5. 2) If it can be determined that Khartoum is now using 127.5 as their Primary frequency; the High Enroute Chart Communications information needs to be updated.

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.