A320 FLT CREW HAS UNSTABILIZED APCH INTO DEN.
Synopsis
A320 FLT CREW HAS UNSTABILIZED APCH INTO DEN.
Narrative
WE EXPERIENCED MODERATE CONTINUOUS TURB FROM FL250 TO THE SURFACE. IT WAS VERY DIFFICULT TO SEE THE PFD AND ND DURING MUCH OF THIS ARR PHASE. ARR ATIS IN EFFECT XMITTED WINDS 230 DEGS AT 19 KTS GUSTING 29 KTS. WE PLANNED FOR; BRIEFED; A VISUAL APCH TO RWY 16L. AT 9000 FT; APPROX 5 MI NE OF LEETS (FAF); WE'RE GIVEN VISUAL APCH CLRNC FOR RWY 16L; 170 KTS TO LEETS. ACFT AT FLAPS 2 DEGS WITH 1/2 SPD BRAKES. ARMED THE ILS APCH AND WERE ABOUT 1 DOT HIGH WITH A HEADWIND AT 8000 FT UPON INTERCEPTING THE LOC. I RETRACTED THE SPD BRAKES. AT GS INTERCEPT; I CALLED FOR FLAPS FULL AS I NOTICED THE GS INDICATOR QUICKLY MOVING DOWN (INDICATING A TAILWIND SHIFT). THE FO SELECTED ONLY FLAPS 3 DEGS; AS WE WERE STILL AT 170 KTS AND AT NO TIME DID WE EXPERIENCE A FLAP OVERSPD. AT THIS POINT; I OBSERVED THE IRS WINDS TO BE SHOWING 285 DEGS/15 KTS JUST AS WE APCHED LEETS. I WAS ABOUT TO CALL FOR GEAR DOWN AS THE FO ATTEMPTED TO CONTACT TWR (WE WERE NOT HANDED OFF BY TRACON) AT LEETS. I DELAYED ASKING FOR THE GEAR UNTIL OUR COM WITH TWR WAS ESTABLISHED. AFTER 2 CALLS; WE GOT NO RESPONSE. I TOLD HIM TO TRY THE OTHER TWR FREQ. THE 1ST TWR CTLR REDIRECTED US TO 2ND TWR CTLR; WHERE WE RECEIVED LNDG CLRNC. AT THIS POINT; WE WERE 1 MI INSIDE OF LEETS AND 1 DOT ABOVE GS AT 170 KTS; FLAPS 3 DEGS. I THEN CALLED FOR GEAR DOWN; FINAL DSCNT CHKLIST AT ABOUT 1300 FT AGL. I HAD TO INCREASE OUR DSCNT RATE TO INTERCEPT THE GS; AND WE RECEIVED A SINK RATE ONE TIME WARNING WITH A SINK RATE OF 1300 FPM. I ADJUSTED TO APPROX 1100 FPM; WITH SPD OF 170 KTS; AUTOTHRUST AT IDLE AND REAPPLIED 1/2 SPD BRAKES. AT THIS POINT; WE HAD APPROX 20 KTS OF TAILWIND. THE LAST WIND RPT WE HAD WAS 230 DEGS AT 19 KTS GUSTING 30 KTS. I ASSUMED (ERRONEOUSLY) THAT WE WOULD VERY QUICKLY GET THE HEADWIND COMPONENT THAT WOULD ALLOW ME TO STABILIZE THE DSCNT RATE TO A 700 FPM STANDARD. WE WERE NOW ON GS AND LOC; WITH THE SPD FINALLY SLOWING FROM 170 KTS. AT ABOUT 700 FT RA; WE GOT THE 'TERRAIN; TERRAIN;' THEN 'TERRAIN; PULL UP' VOICE ALERTS (MODE 2); WHICH SENSES THE CLOSURE RATE WHEN ON GS AND FLAPS NOT IN FULL; BUT IN POS #3. OUR DSCNT WAS BTWN 1000-1100 FPM; AS THE TAILWIND APPARENTLY CONTINUED TO INCREASE CONTRARY TO OUR LATEST ATIS. AS OUR SPD WAS STILL ABOVE VREF; I THOUGHT THIS WAS RELATED TO OUR FLAP 3 DEG POS AND BRIEFED THE FO TO SELECT FLAPS CONF 3 ON THE GPWS CTL PANEL. WE GOT ONE MORE 'TERRAIN; TERRAIN' JUST BELOW 500 FT (AS PRESCRIBED BY GPWS MODE 2) AS AN INDICATION THAT THE WARNING ENVELOPE WAS EXITED. OUR APCH SPD AT THIS POINT WAS STILL CONSIDERABLY ABOVE VREF AT THIS POINT; BUT BELOW 170 KTS; AND DECREASING; AUTOTHRUST ENGAGED; ENGS SHOWING FLT IDLE. THE FLARE WAS AT THE NORMAL ALT (THRUST MANUALLY SELECTED TO IDLE AT 50 FT; FLARE AT ABOUT 10 FT); ALTHOUGH THE GND SPD SEEMED MUCH HIGHER THAN NORMAL. WE DEFINITELY HAD A TAILWIND; PROBABLY BTWN 10-20 KTS. THE TOUCHDOWN WAS AT THE LAST SINGLE TOUCHDOWN BAR ON THE RWY (ABOUT 3000 FT DOWN); WITH A NORMAL LNDG. LOW AUTOBRAKES AND FULL REVERSE THRUST WERE USED; WITH A NORMAL 90 DEG TURN-OFF TO THE L AT F3. WE EXPERIENCED HOT BRAKES ON THE L TRUCK ONLY; NORMAL TEMPS ON THE R TRUCK. THIS WAS PROBABLY CAUSED BY MY MANUAL BRAKE ACTUATION BEYOND THE AUTOBRAKE LOW DECELERATION RATE -- NOT THAT UNUSUAL IN THE A320. UPON OUR CLRING OF THE RWY; TWR VECTORED THE 2 ACFT FOLLOWING US FOR WY 16L AROUND FOR A N LNDG AND CHANGED THE ACTIVE ARRS TO RWYS 34R; 35L; AND 35R. AT XA37; THEY ISSUED A SPECIAL METAR WITH WINDS OF 030 DEGS AT 20 KTS GUSTING 30 KTS. IN RETROSPECT; I SHOULD HAVE GONE AROUND AT 1000 FT WHEN IT BECAME OBVIOUS THAT THE GUSTING AND CHANGING WINDS WERE NOT AS ADVERTISED. I HAD MANY INDICATIONS: EXCESSIVE DSCNT RATE; LATE GEAR EXTENSION; SLOW DECELERATION RATE DURING THE DSCNT; AND FINALLY; THE GPWS WARNINGS RELATED TO THE FLAP SELECTION. SEEING THAT LONG RWY AHEAD OF US TENDS TO MENTALLY MODERATE THE NEED FOR A GAR IN SUCH A CASE; AND I WAS FOCUSED ON THE FACT THAT THE WINDS WOULD SURELY TURN INTO A HEADWIND. WHILE THE LNDG WAS UNEVENTFUL; IT WOULD HAVE BEEN MUCH LESS MEMORABLE FOR ME TO PERFORM A GAR AND DEAL WITH EXTRA DELAY TIME. THIS WAS A CLASSIC CASE OF UNSTABILIZED APCH; YET I WAS FOCUSED ON THE LNDG AND COMFORT IN THE AIRPLANE'S ABILITIES. SOME OF THE CONTRIBUTING FACTORS: EXTREME WINDSHIFT FROM ATIS RPTS TO ACTUAL TOUCHDOWN WINDS. IT WOULD HAVE BEEN HELPFUL FOR THE TWR TO GIVE US AN ACTUAL WIND RPT IF THEY WERE SEEING SUCH A DRAMATIC SHIFT. TRACON FAILURE TO GIVE US A PROPER TWR HDOF; THUS FOCUSING ON THAT DURING A SUBSTANTIAL WINDSHIFT EVENT INSIDE THE FAF; WHEN I SHOULD HAVE BEEN CALLING FOR FINAL CONFIGNS. FAILURE TO BRIEF A FLAPS 3 DEG APCH AND ACTIONS PRIOR TO 1000 FT. FAILURE TO SELECT AUTOBRAKES TO MED. MODERATE CONTINUOUS TURB DURING THE DSCNT AND APCH PHASE; AND THE READABILITY OF THE DISPLAYS DURING THIS ACTIVITY -- ALL OF THE CLUES WERE THERE; I WAS JUST MORE FOCUSED ON THE RWY AND THE ENVIRONMENT OUTSIDE OF THE ACFT. A 'GET-HOME' MINDSET THAT DID NOT LEND TO A GAR. A VERY LONG (12000 FT) DRY RWY -- WITH VISUALLY APPARENT ADEQUATE STOPPING DISTANCE.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.