Narrative:

Still last night was a dramatic case in point illustrating; once again; to me; what dangerous folly it is to depend on the HUD; to wit: the WX at ZZZ was 400 overcast with surface visibility varying from 3/4 to 1 1/2 of a mile (but consistently more than 6000 RVR). A mix of moderate rain and light snow was falling. Winds were out of the north/northwest at about 10 to 15 KTS. I set up for the ILS and briefed and prepared for the approach; setting the HUD for A1 (concerned that even at that level of sensitivity; an excess deviation alert would be triggered in the turbulent and gusty WX). Everything was going fine until we broke out of the WX (approximately over the approach lights). Past experience has taught me that the HUD's symbology is easily washed out in the glare of approach and threshold lighting set at anything above the minimum level. Unfortunately; because I fly ZZZZ; I rarely fly an ILS in low WX and I forgot to ask the tower controller to turn down the lighting as we crossed the FAF. Nevertheless; once the HUD was blinded by the approach lights; I reached up with my right hand an increased the HUD's illumination level; but even at its maximum; the flight path vector and flight director guidance were still all but invisible. Passing the approach lights; the HUD was now set much too high and I reached up to adjust it once again (please don't ask about the automatic illumination function because I've never seen that work well either). Fortunately the VASI; runway; and centerline lights were providing good guidance for continuing to a safe landing or at least; so I thought. Over the runway; the volume of rain increased significantly and the wipers (in high speed) were barely keeping up. Visibility through the windshield was still adequate to make a safe landing; but now the HUD had become the greatest impediment because the guidance function was (once again) invisible and the rest of the HUD's symbols (even in the de-cluttered mode) was only further obscuring my visibility and forcing me to work through its distraction; moreover; with the runway lighting already being diffused by the rain soaked windshield and high speed wipers; the glass of the combiner only added to the problem. The net result was that I flared too high; floated too long and with the left thrust reverser placarded inoperative; and the runway wet; the runway length consumed was far greater than it should have been. In summary: the HUD guidance symbology is washed out to the point of invisibility in the higher settings of approach and runway lighting. Without the flight path vector and flight director guidance cue visible through landing; the HUD has little or no advantage over conventional flight path guidance (ILS; VASI; threshold lighting; centerline lights; and runway lights). When the flight path vector and flight path director guidance cue are not visible; the HUD symbology and combiner are nothing but distractions and impediments to a safe landing in heavy rain. The HUD is not an autoland type device; forward visibility is always required to legally and safely complete a HUD based approach to a landing. Since the HUD is not certified for zero visibility lndgs; then it should not be mandatory for lndgs at any time. In retrospect; I should have executed a missed approach and diverted to an alternate or; returned for another approach (but only after ensuring the approach lights had been set to the lowest possible level). The limitations of the HUD in conjunction with air carrier's mandatory HUD use policy will result in an accident.callback conversation with reporter revealed the following information: the reporter is highly experienced with this system and has nothing but confidence and praise for the technical aspects of its design. He is very concerned about HUD use during visibility restrictions such as snow or moderate rain where runway lights are diffused to the point of restricting fwd visibility; overpowering HUD lights; and consequently preventing the pilot from knowing the aircraft's altitude just prior to touchdown. He is concerned that an aircraft will essentially be out of control at touchdown.

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Original NASA ASRS Text

Title: ACR PILOT DISCUSSES HIS ACR'S REQUIREMENT FOR MANDATORY HUD USE ON APCHES WHEN HIGH RWY LIGHT ILLUMINATION AND PRECIPITATION OBSCURE VISION DURING LNDG.

Narrative: STILL LAST NIGHT WAS A DRAMATIC CASE IN POINT ILLUSTRATING; ONCE AGAIN; TO ME; WHAT DANGEROUS FOLLY IT IS TO DEPEND ON THE HUD; TO WIT: THE WX AT ZZZ WAS 400 OVERCAST WITH SURFACE VISIBILITY VARYING FROM 3/4 TO 1 1/2 OF A MILE (BUT CONSISTENTLY MORE THAN 6000 RVR). A MIX OF MODERATE RAIN AND LIGHT SNOW WAS FALLING. WINDS WERE OUT OF THE NORTH/NORTHWEST AT ABOUT 10 TO 15 KTS. I SET UP FOR THE ILS AND BRIEFED AND PREPARED FOR THE APCH; SETTING THE HUD FOR A1 (CONCERNED THAT EVEN AT THAT LEVEL OF SENSITIVITY; AN EXCESS DEV ALERT WOULD BE TRIGGERED IN THE TURBULENT AND GUSTY WX). EVERYTHING WAS GOING FINE UNTIL WE BROKE OUT OF THE WX (APPROX OVER THE APCH LIGHTS). PAST EXPERIENCE HAS TAUGHT ME THAT THE HUD'S SYMBOLOGY IS EASILY WASHED OUT IN THE GLARE OF APCH AND THRESHOLD LIGHTING SET AT ANYTHING ABOVE THE MINIMUM LEVEL. UNFORTUNATELY; BECAUSE I FLY ZZZZ; I RARELY FLY AN ILS IN LOW WX AND I FORGOT TO ASK THE TWR CTLR TO TURN DOWN THE LIGHTING AS WE CROSSED THE FAF. NEVERTHELESS; ONCE THE HUD WAS BLINDED BY THE APCH LIGHTS; I REACHED UP WITH MY RIGHT HAND AN INCREASED THE HUD'S ILLUMINATION LEVEL; BUT EVEN AT ITS MAXIMUM; THE FLT PATH VECTOR AND FLT DIRECTOR GUIDANCE WERE STILL ALL BUT INVISIBLE. PASSING THE APCH LIGHTS; THE HUD WAS NOW SET MUCH TOO HIGH AND I REACHED UP TO ADJUST IT ONCE AGAIN (PLEASE DON'T ASK ABOUT THE AUTOMATIC ILLUMINATION FUNCTION BECAUSE I'VE NEVER SEEN THAT WORK WELL EITHER). FORTUNATELY THE VASI; RWY; AND CTRLINE LIGHTS WERE PROVIDING GOOD GUIDANCE FOR CONTINUING TO A SAFE LNDG OR AT LEAST; SO I THOUGHT. OVER THE RWY; THE VOLUME OF RAIN INCREASED SIGNIFICANTLY AND THE WIPERS (IN HIGH SPEED) WERE BARELY KEEPING UP. VISIBILITY THROUGH THE WINDSHIELD WAS STILL ADEQUATE TO MAKE A SAFE LNDG; BUT NOW THE HUD HAD BECOME THE GREATEST IMPEDIMENT BECAUSE THE GUIDANCE FUNCTION WAS (ONCE AGAIN) INVISIBLE AND THE REST OF THE HUD'S SYMBOLS (EVEN IN THE DE-CLUTTERED MODE) WAS ONLY FURTHER OBSCURING MY VISIBILITY AND FORCING ME TO WORK THROUGH ITS DISTRACTION; MOREOVER; WITH THE RWY LIGHTING ALREADY BEING DIFFUSED BY THE RAIN SOAKED WINDSHIELD AND HIGH SPEED WIPERS; THE GLASS OF THE COMBINER ONLY ADDED TO THE PROBLEM. THE NET RESULT WAS THAT I FLARED TOO HIGH; FLOATED TOO LONG AND WITH THE LEFT THRUST REVERSER PLACARDED INOP; AND THE RWY WET; THE RWY LENGTH CONSUMED WAS FAR GREATER THAN IT SHOULD HAVE BEEN. IN SUMMARY: THE HUD GUIDANCE SYMBOLOGY IS WASHED OUT TO THE POINT OF INVISIBILITY IN THE HIGHER SETTINGS OF APCH AND RWY LIGHTING. WITHOUT THE FLT PATH VECTOR AND FLT DIRECTOR GUIDANCE CUE VISIBLE THROUGH LNDG; THE HUD HAS LITTLE OR NO ADVANTAGE OVER CONVENTIONAL FLT PATH GUIDANCE (ILS; VASI; THRESHOLD LIGHTING; CTRLINE LIGHTS; AND RWY LIGHTS). WHEN THE FLT PATH VECTOR AND FLT PATH DIRECTOR GUIDANCE CUE ARE NOT VISIBLE; THE HUD SYMBOLOGY AND COMBINER ARE NOTHING BUT DISTRACTIONS AND IMPEDIMENTS TO A SAFE LNDG IN HVY RAIN. THE HUD IS NOT AN AUTOLAND TYPE DEVICE; FORWARD VISIBILITY IS ALWAYS REQUIRED TO LEGALLY AND SAFELY COMPLETE A HUD BASED APCH TO A LNDG. SINCE THE HUD IS NOT CERTIFIED FOR ZERO VISIBILITY LNDGS; THEN IT SHOULD NOT BE MANDATORY FOR LNDGS AT ANY TIME. IN RETROSPECT; I SHOULD HAVE EXECUTED A MISSED APCH AND DIVERTED TO AN ALTERNATE OR; RETURNED FOR ANOTHER APCH (BUT ONLY AFTER ENSURING THE APCH LIGHTS HAD BEEN SET TO THE LOWEST POSSIBLE LEVEL). THE LIMITATIONS OF THE HUD IN CONJUNCTION WITH ACR'S MANDATORY HUD USE POLICY WILL RESULT IN AN ACCIDENT.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE REPORTER IS HIGHLY EXPERIENCED WITH THIS SYSTEM AND HAS NOTHING BUT CONFIDENCE AND PRAISE FOR THE TECHNICAL ASPECTS OF ITS DESIGN. HE IS VERY CONCERNED ABOUT HUD USE DURING VISIBILITY RESTRICTIONS SUCH AS SNOW OR MODERATE RAIN WHERE RWY LIGHTS ARE DIFFUSED TO THE POINT OF RESTRICTING FWD VISIBILITY; OVERPOWERING HUD LIGHTS; AND CONSEQUENTLY PREVENTING THE PILOT FROM KNOWING THE ACFT'S ALT JUST PRIOR TO TOUCHDOWN. HE IS CONCERNED THAT AN ACFT WILL ESSENTIALLY BE OUT OF CONTROL AT TOUCHDOWN.

Data retrieved from NASA's ASRS site as of January 2009 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.