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ASN Wikibase Occurrence # 44869
Last updated: 28 November 2021
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Date:10-MAY-2004
Time:21:00
Type:Silhouette image of generic PA44 model; specific model in this crash may look slightly different
Piper PA-44-180
Owner/operator:Pan Am International Flight Academy
Registration: N304PA
MSN: 4496123
Fatalities:Fatalities: 2 / Occupants: 2
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Category:Accident
Location:Julian, CA -   United States of America
Phase: En route
Nature:Private
Departure airport:Phoenix, AZ (KDVT)
Destination airport:Palomar, CA (KCRQ)
Investigating agency: NTSB
Narrative:
The twin engine airplane collided with rising mountainous terrain while in cruise flight on an IFR clearance. The airplane, N304PA, was on a night IFR flight and was number four in a trail of five company airplanes flying the same route. The time separation between each airplane was about 5 to 10 minutes. The airplane directly ahead of N304PA was N434PA. After being handed off from Los Angeles Center, the flight crew of N304PA contacted the TRACON sector controller at 2043:48 PDT, reporting level at 8,000. The TRACON sector controller instructed the pilot to fly heading 260 after the Julian VOR and intercept the localizer. At 2045:47, the TRACON sector controller told the pilot of N434PA to descend to 6,000 feet. The pilot of N434PA acknowledged the clearance. At 2047:55, the sector controller transmitted, "Seminole four papa alpha descend and maintain five thousand two hundred." The pilot of N304PA responded, "Down to five thousand two hundred for three zero four papa alpha." According to information provided by the TRACON sector controller, this clearance was intended for N434PA. The controller did not recognize that the clearance had been acknowledged by N304PA rather than N434PA. At 2049:55, the pilot of N304PA reported that he had ATIS information Zulu and the sector controller responded, "Seminole three zero four papa alpha thank you very much." At that time the data block on the TRACON controller's display was showing N304PA descending through about 6,600 feet. The Minimum Enroute Altitude for the airway segment being flown was 7,700 feet. At 2050:27, the sector controller again cleared N434PA to descend and maintain 5,200 feet. A Minimum Safe Altitude Warning (MSAW) alert on N304PA was presented to the Center controller at 2049:03. The aircraft's data block remained on the Center controllers display until the radar controller forced it off at 2050:07. The Center controller did not notify the TRACON sector controller that he was receiving a MSAW alert as required by FAA directives. The TRACON's MSAW system generated two predicted altitude alerts on the accident airplane at 2050:46 and 2050:51. According to FAA MSAW documentation, two consecutive predicted alerts will initiate an MSAW warning to the controller working the affected aircraft. Collectively, these alerts would have caused a 5 second aural alert to the sector controller beginning at 2050:51, along with a flashing red "LA" in N304PA's data block from 2050:51 until about 2051:06. The aircraft then descended below radar coverage, the track went into coast status, and the alert terminated. The wreckage of N304PA was located on a ridgeline 200 yards south of the Julian VOR at 5,537 feet msl. No preimpact airplane mechanical anomalies were identified.



Probable Cause: The incorrect use of an abbreviated callsign by the TRACON sector radar controller to issue a descent clearance to N434PA and the sector controllers failure to detect that the clearance had been read back with the full callsign by the pilot of N304PA. Also causal was the pilots failure to question a clearance that descended them below the published Minimum En route Altitude (MEA). Contributing to the accident was the failure of both the Center and TRACON controllers to properly respond to the aural and visual Minimum Safe Altitude Warning System (MSAW) alert.

Sources:

NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20040522X00629&key=1

Location


Revision history:

Date/timeContributorUpdates
28-Oct-2008 00:45 ASN archive Added
30-Mar-2011 13:36 TB Updated [Operator, Source, Narrative]
21-Dec-2016 19:24 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
07-Dec-2017 18:03 ASN Update Bot Updated [Source, Narrative]

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