Flight crew of a saab SF340 descended and turned off of assigned heading due to aircraft icing and inability to hold altitude causing less than standard separation with opposite direction traffic at a lower altitude.

Home

Browse by month

Random

Latest

About

Contact

Attributes
ACN	479942
Time
Date	200007
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	navaid : hto.vortac
State Reference	NY
Altitude	msl bound lower : 16000 msl bound upper : 20000
Environment
Flight Conditions	IMC
Weather Elements	Ice
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc.artcc
Operator	common carrier : air carrier
Make Model Name	SF 340B
Operating Under FAR Part	Part 121
Navigation In Use	other other vortac
Flight Phase	cruise : level
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zdc.artcc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 90 flight time total : 7800 flight time type : 2600
ASRS Report	479942
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Experience	flight time last 90 days : 67 flight time total : 900 flight time type : 67
ASRS Report	480419
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude inflight encounter : weather inflight encounter other non adherence : clearance other spatial deviation
Independent Detector	atc equipment other atc equipment : radar aircraft equipment other aircraft equipment : acft ice protection other flight crewa other flight crewb
Resolutory Action	controller : issued advisory flight crew : took precautionary avoidance action
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	ATC Human Performance Aircraft Environmental Factor Flight Crew Human Performance Weather
Primary Problem	Aircraft

Narrative:

We were filed at FL200. #2 engine was on departure power. Climb was slow at 140 KTS. Trace of ice began about 15000 ft. At cruise, leveloff airspeed was about 155 KTS. Within 1 min it was down to 145 KTS with all icing equipment on. I asked the first officer to call ATC and tell them we needed a descent to FL180. ATC responded with an 'unable due to opposite traffic at 9 mi, FL190.' within a few seconds, airspeed decreased to 140 KTS and I again asked first officer to call ATC with the need to descend and we could take a turn, if necessary. ATC again said unable due to opposite traffic. Within a few seconds, airspeed was 135 KTS and decreasing. Wanting to avoid a stall and uncontrollable aircraft due to ice, I called ATC, told them we were unable to maintain our altitude due to icing and were losing airspeed and that we were descending to FL180 now. I turned 20 degrees left and descended to FL191 rapidly, at which time the TCASII went off with a climb alert -- wanting us to climb at 4000 FPM. I had heard ATC tell the other traffic to climb to FL210 immediately. I held the altitude that I had (during the TCASII alert) FL190 plus 500 ft, until the other aircraft had passed then descended to FL180. (I should have declared an emergency, but all this happened fairly rapidly.) FL180 was still too heavy on ice so we went to 16000 ft, and on to rdu (from jfk). A malfunction occurred at FL180 with the boot system and that may have been a contributor to our inability to shed more ice.

Original NASA ASRS Text

Title: FLC OF A SAAB SF340 DSNDED AND TURNED OFF OF ASSIGNED HDG DUE TO ACFT ICING AND INABILITY TO HOLD ALT CAUSING LTSS WITH OPPOSITE DIRECTION TFC AT A LOWER ALT.

Narrative: WE WERE FILED AT FL200. #2 ENG WAS ON DEP PWR. CLB WAS SLOW AT 140 KTS. TRACE OF ICE BEGAN ABOUT 15000 FT. AT CRUISE, LEVELOFF AIRSPD WAS ABOUT 155 KTS. WITHIN 1 MIN IT WAS DOWN TO 145 KTS WITH ALL ICING EQUIP ON. I ASKED THE FO TO CALL ATC AND TELL THEM WE NEEDED A DSCNT TO FL180. ATC RESPONDED WITH AN 'UNABLE DUE TO OPPOSITE TFC AT 9 MI, FL190.' WITHIN A FEW SECONDS, AIRSPD DECREASED TO 140 KTS AND I AGAIN ASKED FO TO CALL ATC WITH THE NEED TO DSND AND WE COULD TAKE A TURN, IF NECESSARY. ATC AGAIN SAID UNABLE DUE TO OPPOSITE TFC. WITHIN A FEW SECONDS, AIRSPD WAS 135 KTS AND DECREASING. WANTING TO AVOID A STALL AND UNCTLABLE ACFT DUE TO ICE, I CALLED ATC, TOLD THEM WE WERE UNABLE TO MAINTAIN OUR ALT DUE TO ICING AND WERE LOSING AIRSPD AND THAT WE WERE DSNDING TO FL180 NOW. I TURNED 20 DEGS L AND DSNDED TO FL191 RAPIDLY, AT WHICH TIME THE TCASII WENT OFF WITH A CLB ALERT -- WANTING US TO CLB AT 4000 FPM. I HAD HEARD ATC TELL THE OTHER TFC TO CLB TO FL210 IMMEDIATELY. I HELD THE ALT THAT I HAD (DURING THE TCASII ALERT) FL190 PLUS 500 FT, UNTIL THE OTHER ACFT HAD PASSED THEN DSNDED TO FL180. (I SHOULD HAVE DECLARED AN EMER, BUT ALL THIS HAPPENED FAIRLY RAPIDLY.) FL180 WAS STILL TOO HVY ON ICE SO WE WENT TO 16000 FT, AND ON TO RDU (FROM JFK). A MALFUNCTION OCCURRED AT FL180 WITH THE BOOT SYS AND THAT MAY HAVE BEEN A CONTRIBUTOR TO OUR INABILITY TO SHED MORE ICE.

Data retrieved from NASA's ASRS site as of July 2007 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.