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Flight crew of a canadair regional jet CL65 climbed in response to a GPWS alarm during radar vectors to final. The vectoring altitude was 400 ft below the MSA depicted on the instrument approach chart.
| Attributes | |
| ACN | 421021 |
| Time | |
| Date | 199811 |
| Day | Wed |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : roa airport : roa |
| State Reference | VA |
| Altitude | msl bound lower : 5000 msl bound upper : 5000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | tracon : roa |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Transport, Low Wing, 2 Turbojet Eng |
| Navigation In Use | Other Other |
| Flight Phase | descent : approach |
| Route In Use | arrival other enroute : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 100 flight time total : 13920 flight time type : 100 |
| ASRS Report | 421021 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : instrument pilot : commercial |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | controller : issued new clearance flight crew : took evasive action |
| Consequence | faa : reviewed incident with flight crew |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | other |
Narrative:
MSA 5400 ft, MVA 5000 ft. During vectors at 5000 ft, GPWS warned 'terrain, terrain, pull up.' PF applied thrust, disconnected autoplt and initiated climb to 6000 ft. Controller later advised that other operators occasionally experienced GPWS warnings in that same area due to a particularly high peak. Approach vectored us back for another approach which was uneventful. Callback conversation with reporter revealed the following information: reporter stated that he called and discussed this matter with approach control personnel who advised that their MVA was 5000 ft. Further, that there had been other flcs complaining about having to respond to a GPWS warning in the same area. He did not know what particular mountain peak to which the controller was referring other than one of the peaks in the southwest quadrant from the airport. He stated that he remembered that the first officer flying pulled up at once when hearing the terrain warning, which would be a warning alert for closure rate only and not the 'pull up, pull up' warning of immediate danger. This type of warning would be a result of a descent rate, or level flight, closure toward rising terrain similar to the terrain toward which the aircraft was flying while coming from the north side of the lda runway 6 final course, to which the reporter was being vectored, at approximately 10 mi out. The reporter further stated that there have been many flight crew complaints with GPWS warnings at night at roa when ZDC handles the approach control functions because they have a 6000 ft MVA instead of 5000 ft. It seems the higher altitude used causes the flight crew to descend at a higher rate when cleared for the approach due to the higher altitude. This then causes GPWS warnings. Therefore, the flight crew finds it better to have the lower altitudes so when cleared for the approach, the rate of descent is more normal.
Original NASA ASRS Text
Title: FLC OF A CANADAIR REGIONAL JET CL65 CLBED IN RESPONSE TO A GPWS ALARM DURING RADAR VECTORS TO FINAL. THE VECTORING ALT WAS 400 FT BELOW THE MSA DEPICTED ON THE INST APCH CHART.
Narrative: MSA 5400 FT, MVA 5000 FT. DURING VECTORS AT 5000 FT, GPWS WARNED 'TERRAIN, TERRAIN, PULL UP.' PF APPLIED THRUST, DISCONNECTED AUTOPLT AND INITIATED CLB TO 6000 FT. CTLR LATER ADVISED THAT OTHER OPERATORS OCCASIONALLY EXPERIENCED GPWS WARNINGS IN THAT SAME AREA DUE TO A PARTICULARLY HIGH PEAK. APCH VECTORED US BACK FOR ANOTHER APCH WHICH WAS UNEVENTFUL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT HE CALLED AND DISCUSSED THIS MATTER WITH APCH CTL PERSONNEL WHO ADVISED THAT THEIR MVA WAS 5000 FT. FURTHER, THAT THERE HAD BEEN OTHER FLCS COMPLAINING ABOUT HAVING TO RESPOND TO A GPWS WARNING IN THE SAME AREA. HE DID NOT KNOW WHAT PARTICULAR MOUNTAIN PEAK TO WHICH THE CTLR WAS REFERRING OTHER THAN ONE OF THE PEAKS IN THE SW QUADRANT FROM THE ARPT. HE STATED THAT HE REMEMBERED THAT THE FO FLYING PULLED UP AT ONCE WHEN HEARING THE TERRAIN WARNING, WHICH WOULD BE A WARNING ALERT FOR CLOSURE RATE ONLY AND NOT THE 'PULL UP, PULL UP' WARNING OF IMMEDIATE DANGER. THIS TYPE OF WARNING WOULD BE A RESULT OF A DSCNT RATE, OR LEVEL FLT, CLOSURE TOWARD RISING TERRAIN SIMILAR TO THE TERRAIN TOWARD WHICH THE ACFT WAS FLYING WHILE COMING FROM THE N SIDE OF THE LDA RWY 6 FINAL COURSE, TO WHICH THE RPTR WAS BEING VECTORED, AT APPROX 10 MI OUT. THE RPTR FURTHER STATED THAT THERE HAVE BEEN MANY FLC COMPLAINTS WITH GPWS WARNINGS AT NIGHT AT ROA WHEN ZDC HANDLES THE APCH CTL FUNCTIONS BECAUSE THEY HAVE A 6000 FT MVA INSTEAD OF 5000 FT. IT SEEMS THE HIGHER ALT USED CAUSES THE FLC TO DSND AT A HIGHER RATE WHEN CLRED FOR THE APCH DUE TO THE HIGHER ALT. THIS THEN CAUSES GPWS WARNINGS. THEREFORE, THE FLC FINDS IT BETTER TO HAVE THE LOWER ALTS SO WHEN CLRED FOR THE APCH, THE RATE OF DSCNT IS MORE NORMAL.
Data retrieved from NASA's ASRS site as of July 2007 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.