A B737 CAPT GETS A MOMENTARY GPWS TERRAIN WARNING ON APPROACH TO RNO. WARNING CEASED BEFORE FLT CREW COULD RESPOND.

Date: 2007-04 · Aircraft: B737-700

Anomalies: inflight-event-encounter-cftt-cfit|inflight-event-encounter-weather-turbulence

Synopsis

A B737 CAPT GETS A MOMENTARY GPWS TERRAIN WARNING ON APPROACH TO RNO. WARNING CEASED BEFORE FLT CREW COULD RESPOND.

Narrative

FLT ORIGINALLY DISPATCHED FOR A PLANNED ARR ON RNO RWY 16R. WX OBSERVED INCLUDED WINDS: 180 DEGS AT 4 KTS. TURB PLOT INFO INCLUDED ROTOR ACTIVITY FROM 700 FT MSL TO 15000 FT MSL FOR OUR ARR TIME. FORECAST ARR WINDS WERE 200 DEGS AT 6 KTS CHANGING AT XB00Z TO 210 DEGS AT 10 KTS GUSTING TO 20 KTS P6M VCSH SCATTERED 80 BROKEN 120. PRIOR TO TOP OF DSCNT; WE BRIEFED AND PLANNED A RWY 16R VISUAL ARR. XA56Z ATIS INDICATED A RWY 34L ARR. WE BRIEFED A VISUAL ARR TO RWY 34L; CAREFULLY ADDRESSING THE TERRAIN ISSUES AND CONCERNS TO INCLUDE A POTENTIAL MISSED APCH AND A PROPER RESPONSE TO A GPWS TERRAIN WARNING. UNDER RNO APCH CTL; WE CONTINUED IN LNAV TOWARD FMG WITH CLRNC TO 10000 FT MSL AND SUBSEQUENT CLRNC TO 9000 FT MSL; GIVEN 160 DEG HDG AND MAINTAIN 9000 FT XING FMG. AFTER XING FMG; RNO APCH ASKED IF WE COULD MAINTAIN VISUAL CONTACT WITH THE FIELD. WE DECLINED BECAUSE VIRGA PARTIALLY OBSCURED CONTINUOUS CONTACT WITH THE FIELD. RNO APCH THEN DIRECTED US TO 8400 FT MSL WITH PLANS TO 'CLR US FOR THE VISUAL.' AT 8400 FT MSL WE AGAIN INFORMED RNO APCH WE COULD NOT MAINTAIN VISUAL CONTACT WITH THE FIELD. RNO APCH RECLRED US TO 9000 FT MSL. WE COMPLIED IMMEDIATELY. LEVEL AT 9000 FT MSL; WE EXPERIENCED CONTINUOUS LIGHT TURB WITH WIND DIRECTION IN HUD CHANGING RANDOMLY. WE WERE IN CONSTANT VISUAL CONTACT WITH THE GND; BUT THE PLT MONITORING RPTED HE HAD LOST THE FIELD. RNO APCH THEN ADVISED US TO EXPECT VECTORS TO THE RWY 34R LOC BACK COURSE. IN THE NEXT MOMENT WE HEARD 'TERRAIN; TERRAIN.' BEFORE I COULD RESPOND; THE WARNING CEASED AND RNO APCH DIRECTED A CLB TO 10000 FT MSL. I BEGAN THE CLB IMMEDIATELY. AT 10000 FT WE LOST SIGHT OF THE GND. WE WERE EVENTUALLY VECTORED FOR THE RNO 34 LOC BACK COURSE. STRONG TAILWINDS PRECLUDED A SAFE DSCNT FOR THE PUBLISHED PROC. WE NOTIFIED RNO APCH; EXECUTED A MISSED APCH AND WERE SUBSEQUENTLY VECTORED TO RNO RWY 16R ILS. FROM THE MOMENT WE BEGAN THE MISSED APCH; WE HEARD CONSTANT RADIO DISCUSSION OF CONTINUOUS TURB AND GUSTING WINDS FROM THE S; INCLUDING WINDSHEAR RPTS AND ADVISORIES. THE CPR JET WE FOLLOWED ON APCH TO RWY 16R RPTED '+20K AT 400 FT AGL.' WE EXPERIENCED +/-10000 FT ALL THE WAY DOWN FINAL TO 100 FT AGL IN VMC. TOUCHDOWN AND BRAKING WERE UNEVENTFUL. I FULLY UNDERSTAND THE LATEST RNO COMMERCIAL CHART PAGE GUIDANCE AS WELL AS THE FOM GUIDANCE CONCERNING EGPWS 'TERRAIN' WARNINGS. FURTHERMORE; I HAD AND STILL HAVE EVERY INTENTION OF COMPLYING; EVERY TIME! WE EVEN BRIEFED THE PROC BEFORE WE ARRIVED IN THE RENO AREA. HOWEVER; THE WARNING WAS INCOMPLETE (ONE QUICK 'TERRAIN; TERRAIN' AND NOTHING MORE). IT STOPPED AS SUDDENLY AS IT BEGAN; WITHOUT ANY ATTITUDE CHANGE. I PLAN TO TALK WITH SOMEONE EXTENSIVELY ABOUT THIS; TO INCLUDE SOME OF THE 'SCIENCE' BEHIND THE EGPWS.

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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.