Narrative:

We were cleared for the RNAV GPS Z approach. We had slowed to 250 KTS. The first officer who was flying had the autopilot coupled with approach in green and engaged; he called for the missed approach altitude to be set and as we crossed [the next fix]; the aircraft made a sharp nose over descent to stay on profile. In an attempt to slow the aircraft the first officer called for gear down. Thinking we had been below the 250 KTS maximum gear extension speed; I selected the gear handle to the down position. Nothing happened..... I waited about 3 seconds and cycled the handle up and then down a second time. Again nothing..... I repeated the recycle of the gear handle one more time with no gear response. At that point I raised the gear handle back up and told the first officer that we would do a soft go-around. I announced to tower that we were having issues with our landing gear and that we needed to go-around and wanted vectors to an area we could sort out our problem. I declared an emergency at that time. We initiated the go-around at approximately 3;400 ft the tower gave us instructions to maintain the runway heading and climb to 4;000 ft. The first officer continued the fly the aircraft as I pulled my QRH out to start the troubleshooting process. The tower turned us to the southwest and handed us off to approach control. I notified the flight attendants of our situation and told them I would get back to them when I knew what we were dealing with. I also had instructed the first officer to slow the aircraft to 220 KTS to give us more time to work our problem. As I opened the QRH to the landing gear section; I noticed that there were 13 different scenarios and none really stood out as fitting our situation. So for whatever reason I reached over and placed the land gear lever down a fourth time. The gear extended and I had all green gear safe indications. With our gear now down I told approach control we now had safe gear and would like vectors back for an ILS. I told him to inform tower that we requested crash fire rescue equipment to standby as a precaution. I notified the flight attendants that I anticipated a normal landing and I then notified the passengers that we had received unsafe gear indications earlier on approach; but now had safe gear indications. [I] also told the passengers that crash fire rescue equipment would be standing by as a precaution. We were vectored back around for an ILS/visual approach and landed without any further issues. I believe this event occurred due to different factors.............. 1.) it would appear that the speed limiter (260 KTS) was exceeded preventing the landing gear from extending the first time. With the gear handle being placed down just after the sudden pitch down of the aircraft on the approach; the speed limiter which gets its data from adr 1 and adr 3 detected too high a speed. I personally never saw my airspeed indicator higher than about 255 KTS at pitch down; but the adrs detected higher speeds. 2.) in my follow up research; it would appear that if the speed limiter is exceeded the gear handle needs to be in the up position for at least 2 minutes to reset the system. So the second and third try to extend the gear which came in rapid succession after the first; were a futile attempt since the 2 minute time had not expired. 3.) this arrival as many other arrivals in our system are fairly complex and steep. It is not unusual to receive a message on the mcdu .... 'To steep path ahead'. With these steep angled RNAV arrivals; the A321 is always having to use speedbrakes; flaps and gear near their max limits to accomplish a successful approach to land. In the ten or more years I have been flying the A320 series aircraft I have never experienced the gear speed limiter. This feature along with the 2 minute reset time limit needs to be pointed out to crews during recurrent training. We had to dig to find the specifics of this system. It's my prediction that as more steep angled RNAV arrivals are flown; the possibility of this happening again to someone else is great. If we had recognized exactly what had really happened; both the crew and maintenance would be better prepared to handle this in a more efficient manner. I also think that many of the RNAV arrivals we do need to be re-evaluated and reassigned more gradual and more reasonable speed parameters.

Related reports:

Google
 

Original NASA ASRS Text

Title: A321 Captain experiences a failure of the landing gear to extend when needed for drag on a steep RNAV approach. After repeated attempts without success a go-around is initiated. The A321 QRH does not have a procedure and no faults were indicated. Another attempt at extending the gear is successful and a normal landing ensues. The steep descent required on the approach was also brought into question. Post flight revealed that the first extension attempt had been blocked by automatic systems due speed above 260 KTS and subsequent attempts were blocked by a two minute time delay from the initial attempt in the same system.

Narrative: We were cleared for the RNAV GPS Z approach. We had slowed to 250 KTS. The First Officer who was flying had the autopilot coupled with APPROACH in green and engaged; He called for the missed approach altitude to be set and as we crossed [the next fix]; the aircraft made a sharp nose over descent to stay on profile. In an attempt to slow the aircraft the First Officer called for gear down. Thinking we had been below the 250 KTS maximum gear extension speed; I selected the gear handle to the down position. Nothing happened..... I waited about 3 seconds and cycled the handle up and then down a second time. Again nothing..... I repeated the recycle of the gear handle one more time with no gear response. At that point I raised the gear handle back up and told the First Officer that we would do a soft go-around. I announced to Tower that we were having issues with our landing gear and that we needed to go-around and wanted vectors to an area we could sort out our problem. I declared an emergency at that time. We initiated the go-around at approximately 3;400 FT the Tower gave us instructions to maintain the runway heading and climb to 4;000 FT. The First Officer continued the fly the aircraft as I pulled my QRH out to start the troubleshooting process. The Tower turned us to the southwest and handed us off to Approach Control. I notified the flight attendants of our situation and told them I would get back to them when I knew what we were dealing with. I also had instructed the First Officer to slow the aircraft to 220 KTS to give us more time to work our problem. As I opened the QRH to the landing gear section; I noticed that there were 13 different scenarios and none really stood out as fitting our situation. So for whatever reason I reached over and placed the land gear lever down a fourth time. The gear extended and I had all green gear safe indications. With our gear now down I told Approach Control we now had safe gear and would like vectors back for an ILS. I told him to inform Tower that we requested CFR to standby as a precaution. I notified the flight attendants that I anticipated a normal landing and I then notified the passengers that we had received unsafe gear indications earlier on approach; but now had safe gear indications. [I] also told the passengers that CFR would be standing by as a precaution. We were vectored back around for an ILS/VISUAL approach and landed without any further issues. I believe this event occurred due to different factors.............. 1.) It would appear that the speed limiter (260 KTS) was exceeded preventing the landing gear from extending the first time. With the gear handle being placed down just after the sudden pitch down of the aircraft on the approach; the speed limiter which gets its data from ADR 1 and ADR 3 detected too high a speed. I personally never saw my airspeed indicator higher than about 255 KTS at pitch down; but the ADRs detected higher speeds. 2.) In my follow up research; it would appear that if the speed limiter is exceeded the gear handle needs to be in the up position for at least 2 minutes to reset the system. So the second and third try to extend the gear which came in rapid succession after the first; were a futile attempt since the 2 minute time had not expired. 3.) This arrival as many other arrivals in our system are fairly complex and steep. It is not unusual to receive a message on the MCDU .... 'To Steep Path Ahead'. With these steep angled RNAV arrivals; the A321 is always having to use speedbrakes; flaps and gear near their max limits to accomplish a successful approach to land. In the ten or more years I have been flying the A320 series aircraft I have never experienced the gear speed limiter. This feature along with the 2 minute reset time limit needs to be pointed out to crews during recurrent training. We had to dig to find the specifics of this system. It's my prediction that as more steep angled RNAV arrivals are flown; the possibility of this happening again to someone else is great. If we had recognized exactly what had really happened; both the crew and Maintenance would be better prepared to handle this in a more efficient manner. I also think that many of the RNAV arrivals we do need to be re-evaluated and reassigned more gradual and more reasonable speed parameters.

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.