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Air carrier PIC accepts approach controller's descent clearance to an unauthorized altitude which is below sector, approach transition and ILS intercept altitude. Aircraft was in VMC conditions.
| Attributes | |
| ACN | 145437 |
| Time | |
| Date | 199005 |
| Day | Thu |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : iad |
| State Reference | VA |
| Altitude | msl bound lower : 2000 msl bound upper : 4000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : iad |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Navigation In Use | Other Other |
| Flight Phase | cruise other cruise other descent other |
| 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 : commercial pilot : atp |
| Experience | flight time last 90 days : 200 flight time total : 12000 flight time type : 600 |
| ASRS Report | 145437 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 80 flight time total : 9000 flight time type : 2000 |
| ASRS Report | 145005 |
| Events | |
| Anomaly | non adherence : published procedure non adherence other other anomaly other |
| Independent Detector | other flight crewa |
| Resolutory Action | controller : issued new clearance flight crew : exited adverse environment |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Ambiguous |
| Air Traffic Incident | Pilot Deviation Operational Deviation other |
Narrative:
We called approach to confirm 4000' and the controller responded, 'roger, now cleared to 2000'.' first officer and I discussed 2000' and called for another confirmation of 2000' as we were north of iad. He rogered, 'air carrier X to 2000'.' at the time we were VFR below an overcast and we accepted the 2000'. When at 2000', I called the controller and complained. That 2000' seemed a little low in an active GA area. The controller responded with, 'I thought you were at 4000'. No problem, but climb to 3000' while intercepting ILS 19R localizer.' he left the impression he was thinking 4000' and said 2000'. Possibly since he had planned for us to use 12 and then switched to 19R, caused the miscom. Had we not confirmed the altitude twice and been VFR, we would not have descended below the sector altitude--but the potential is obvious. Whatever the combination of events, the resulting verbal communications ended in a very low altitude clearance. Supplemental information from acn 145005: the controller then said, 'I thought I cleared you to 4000--climb to 3000.' he (controller) apologized for the error.
Original NASA ASRS Text
Title: ACR PIC ACCEPTS APCH CTLR'S DESCENT CLRNC TO AN UNAUTH ALT WHICH IS BELOW SECTOR, APCH TRANSITION AND ILS INTERCEPT ALT. ACFT WAS IN VMC CONDITIONS.
Narrative: WE CALLED APCH TO CONFIRM 4000' AND THE CTLR RESPONDED, 'ROGER, NOW CLRED TO 2000'.' F/O AND I DISCUSSED 2000' AND CALLED FOR ANOTHER CONFIRMATION OF 2000' AS WE WERE N OF IAD. HE ROGERED, 'ACR X TO 2000'.' AT THE TIME WE WERE VFR BELOW AN OVCST AND WE ACCEPTED THE 2000'. WHEN AT 2000', I CALLED THE CTLR AND COMPLAINED. THAT 2000' SEEMED A LITTLE LOW IN AN ACTIVE GA AREA. THE CTLR RESPONDED WITH, 'I THOUGHT YOU WERE AT 4000'. NO PROB, BUT CLB TO 3000' WHILE INTERCEPTING ILS 19R LOC.' HE LEFT THE IMPRESSION HE WAS THINKING 4000' AND SAID 2000'. POSSIBLY SINCE HE HAD PLANNED FOR US TO USE 12 AND THEN SWITCHED TO 19R, CAUSED THE MISCOM. HAD WE NOT CONFIRMED THE ALT TWICE AND BEEN VFR, WE WOULD NOT HAVE DSNDED BELOW THE SECTOR ALT--BUT THE POTENTIAL IS OBVIOUS. WHATEVER THE COMBINATION OF EVENTS, THE RESULTING VERBAL COMS ENDED IN A VERY LOW ALT CLRNC. SUPPLEMENTAL INFO FROM ACN 145005: THE CTLR THEN SAID, 'I THOUGHT I CLRED YOU TO 4000--CLB TO 3000.' HE (CTLR) APOLOGIZED FOR THE ERROR.
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.