A320
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 210; Flight Crew Total 18600; Flight Crew Type 13500
Human-Machine Interface; Situational Awareness
Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Undershoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Aircraft; Human Factors
Cleared to cross FUBBR intersection at FL270 from our cruise altitude of FL290. Pilot flying entered correct crossing altitude at FUBBR in FMGC. Ordinary tailwind present. Pilot flying initiated DES at top of descent point; approximately 6 NM from FUBBR. Autoflight was on and descent was on profile until ALT* mode entered. I suggested that pilot flying hand fly the level off since we were now trending high. pilot flying instead deployed speedbrakes. Only after I told him to hand fly did he do so and we still passed FUBBR at FL274; 400 FT high. Two recurring items; again illustrated here. ALT* is an altitude capture mode. Deploying speed brakes will not affect the level off profile. It will alter your current speed and eventually autothrust will respond but in ALT* you will continue on the level off profile calculated by the autoflight system. If you were going to miss your altitude before you took action; after only deploying speed brakes you will still miss your crossing altitude. Somehow this is not taught or not absorbed by pilots who haven't seen enough of this to understand. Our training should emphasize that once the autoflight enters ALT*; if you want to change the descent trajectory you must either change the pitch mode (which in that time frame can require a lot of crew coordination in very short order) or you must hand fly the level off. And this leads to the second recurring issue this event illustrates; tremendous reluctance to simply disconnect the autopilot and make the airplane do as you would like.Somewhere within the span of my career we have gone from a distrust of autoflight to a distrust of hand flying. That is now being addressed industry-wide in response to accidents; but we all can immediately work to reverse this among ourselves by encouraging hand flying. If our choice is to miss an assigned altitude at a crossing or to disconnect the autoflight and hand fly the airplane as cleared; how have we come to accept the former? We should be hand flying climbs and descents on a regular basis and leave the autoflight for cruise flight or task saturated irregularities. We will find that those complex RNAV SIDS and STARS and routine flying become far simpler when we insert ourselves into the operation of the airplane and depend less on automation.
A320 Captain describes a missed crossing restriction with the First Officer flying and the lack of understanding of the autopilot capture mode (ALT*).