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A B737 pilot reported that the HUD unexpectedly extended to the full down position and could have hit the captain's head. A double locking mechanism may prevent such an event.
| Attributes | |
| ACN | 927622 |
| Time | |
| Date | 201101 |
| Aircraft 1 | |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Landing |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Heads-Up Display |
| Person 1 | |
| Function | Pilot Flying Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical |
Narrative:
Twice in the last several years; I've had the HUD unexpectedly fall from the full up position to the full down position; just missing impact with my head. The first time the HUD dropped came after a firm landing. The second; most recent event occurred two days ago while performing a max thrust takeoff. In both cases; I probably did not raise the HUD up firmly enough to cause it to lock completely. However; I'm sure I'm not the only pilot ever to make that mistake. Should this HUD ever impact someone's skull; it could do some pretty good damage. I suggest that a double locking mechanism be installed to prevent the HUD from falling all the way down from a full up position. I think a second latch at the midpoint would be a good idea. This would require the pilot to manually unlock it twice on the way down from the up position. This would be a minor issue and be as easy as unlocking it from the up position. A huge benefit would be the protection provided the pilot in the case where it's raised enough to stay but not lock. With the second lock installed; the HUD would stop before head impact. Another solution would be rigging something to prevent the HUD from staying up if it isn't fully locked.
Original NASA ASRS Text
Title: A B737 pilot reported that the HUD unexpectedly extended to the full down position and could have hit the Captain's head. A double locking mechanism may prevent such an event.
Narrative: Twice in the last several years; I've had the HUD unexpectedly fall from the full up position to the full down position; just missing impact with my head. The first time the HUD dropped came after a firm landing. The second; most recent event occurred two days ago while performing a max thrust takeoff. In both cases; I probably did not raise the HUD up firmly enough to cause it to lock completely. However; I'm sure I'm not the only pilot ever to make that mistake. Should this HUD ever impact someone's skull; it could do some pretty good damage. I suggest that a double locking mechanism be installed to prevent the HUD from falling all the way down from a full up position. I think a second latch at the midpoint would be a good idea. This would require the pilot to manually unlock it twice on the way down from the up position. This would be a minor issue and be as easy as unlocking it from the up position. A huge benefit would be the protection provided the pilot in the case where it's raised enough to stay but not lock. With the second lock installed; the HUD would stop before head impact. Another solution would be rigging something to prevent the HUD from staying up if it isn't fully locked.
Data retrieved from NASA's ASRS site as of April 2012 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.