Palm Springs, CA, USA
N6479D
Cessna 172N
N84PB
Piper PA-28-140
A high-wing airplane and low-wing airplane collided in mid-air while operating in the traffic pattern at a controlled airport. The air traffic controller issued traffic advisories to both aircraft, and each pilot acknowledged the advisories. The controller also requested that the low-wing airplane, which was inbound to the airport, to "report two miles out on the forty five." The pilot of the low-wing airplane acknowledged the request; however, there was no evidence that the pilot gave the report. The high-wing airplane was in the process of making a right turn from crosswind to the downwind leg when the low-wing airplane (inbound on a 30 degree entry to downwind) impacted the high-wing airplane's left wing with its propeller and lower engine cowling. The high-wing airplane subsequently lost control, the flight instructor recovered, and conducted an emergency landing in a desert area adjacent to the airport. The low-wing airplane continued to the airport and landed without further incident. Review of the air traffic control system revealed that the control tower was not utilizing the Digital Bright Radar Indicator Tower Equipment (D-BRITE), which would provide controllers with additional radar data on the airplanes, because it was out of service due to being unreliable. However, FAA directives state that the D-BRITE system was never intended to be utilized for traffic separation. The pilots were informed that they did not have radar coverage while in the controlled airspace via the Automatic Terminal Information Service. Additionally, the Airman's Information Manual states that regardless of radar coverage, pilots have the sole responsibility to see and avoid other aircraft.
HISTORY OF FLIGHT On February 15, 2000, at 1729 Pacific standard time, a Cessna 172N high-wing airplane, N6479D, collided in midair with a Piper PA-28-140 low-wing airplane, N84PB, while in the traffic pattern at the Palm Springs International Airport (PSP), Palm Springs, California. The Cessna was substantially damaged and the certified flight instructor and two students received minor injuries. The Piper sustained minor damage; however, neither the certified flight instructor nor the student were injured. The Cessna and the Piper were registered to private individuals and were being operated as instructional flights under 14 Code of Federal Regulations Part 91. The Cessna was operated by Bermuda Dunes Air Service of Bermuda Dunes, California, and the Piper was operated by Alliance International Aviation, Chino, California. The Cessna was originating from PSP at the time of the accident, while the Piper flight had originated from the Chino Airport, Chino, California, about 1650, and was destined for PSP. Visual meteorological conditions prevailed at the time and no flight plans were filed. Review of air traffic control radar data and communications by the National Transportation Safety Board revealed the following information: At 1719:01, N84PB initiated contact with PSP Air Traffic Control Tower (ATCT) Approach Control. The approach controller radar identified N84PB 14 nautical miles west-northwest of PSP. The pilot advised the controller that he had Automatic Terminal Information Service (ATIS) information golf and intended on landing at PSP. The approach controller issued N84PB a transponder code of 0402, and instructed N84PB to "follow the 10 freeway at or above 2,500 feet for right traffic runway 31L." The pilot acknowledged the instructions. At 1723:40, the approach controller instructed N84PB to contact PSP tower on frequency 119.7, to which the pilot acknowledged. When the approach controller handed off N84PB to the control tower, the airplane was located approximately 7 nautical miles northwest of the airport. Meanwhile, prior to N84PD's switch to the control tower frequency, N6479D called ground control and requested "taxi for touch and goes" at 1720:27. Ground control instructed N6479D to taxi to runway 31R. At 1723, N6479D called the PSP local controller and advised that they were "holding short of 31R for touch and goes." At 1724:22, N84PB called the local controller and reported "over the 10 freeway at 3,000 for landing with information golf." At that point, N84PB was approximately 5.5 nautical miles from the center of the airport. The local controller acknowledged and instructed N84PB to "make right traffic runway three one right report two miles out on the forty five." The pilot of N84PB replied "three one right report two miles out, papa bravo." After clearing other traffic, the local controller cleared N6479D at 1725:21, to "follow the Cessna upwind right closed traffic approved, runway three one right, cleared for takeoff." At 1725:39, the local controller advised N84PD that "two Cessnas in the right closed traffic pattern." The pilot replied "papa bravo, looking." At this time, N84PB was 3.5 nautical miles from the center of the airport, or 3.1 miles from the departure end of runway 31R. This position equated with approximately 2.5 nautical miles from a point abeam the departure end of runway 31R on a downwind leg. Radar data indicated that N84PB's ground track was turning to the right, and was passing through 2,400 feet with a descent rate of approximately 600 feet per minute. At 1726:07, the local controller advised N6479D that "traffic's inbound from the northwest for right traffic, a Cherokee." The pilot of N6479D acknowledged. At this point, radar data depicted N6479D established on the upwind leg, approximately over the departure end of 31R. N84PB was approximately 2.5 nautical miles northeast of the departure end of 31R with a ground track of approximately 165 degrees magnetic. At 1726:30, N84PB passed approximately 2 nautical miles north of the departure end of runway 31R. At 1726:48, N84PB passed approximately 2 nautical miles north of the airport center point. No other transmissions or interference were heard on the recorded tower voice communications between 1726:48 and 1727:19. Radar data indicated that the aircraft targets merged approximately 1 nautical mile northeast of the airport at 1,300 feet msl. The Cessna was in a right banked turn to the downwind. The Piper was entering the downwind on about a 30-degree intercept angle. At 1727:20, the pilot of N6479D transmitted a mayday call indicating that they had collided with another airplane and the pilot was having trouble controlling the airplane. The airplane entered an uncommanded descending left spiral. The flight instructor took over control of the airplane, recovered, and performed a forced landing to desert terrain. The local controller observed the airplane perform a forced landing in an open desert area northeast of the airport. After the impact, N84PB requested a low pass to have the local controller observe the landing gear condition. The local controller cleared N84PB for a fly-by at tower level and reported that the landing gear appeared to "be correct." The local controller then cleared N84PB for landing on 31R and at 1733:29, N84PB landed without further incident. During post-accident interviews with both flight instructors, each acknowledged receiving a traffic advisory; however, neither instructor reported seeing the other aircraft at any time prior to the collision. PERSONNEL INFORMATION The flight instructor for the Cessna airplane held instructor ratings in single engine, multiengine, and instrument airplanes. He also held a commercial pilot certificate with ratings for single engine, multiengine, and instrument airplanes. The flight instructor was issued a first-class medical certificate with no limitations on January 11, 2000. According to the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2), the flight instructor accumulated a total of 1,431 flight hours, of which 423 hours were accumulated in the same make and model as the accident airplane. He also reported having accumulated a total of 423 hours of instructor flight hours, of which 335 hours were instructed in the same make and model as the accident airplane. The student, who was flying the Cessna airplane at the time of the accident, had accumulated 25 hours of total flight time, of which all 25 hours were accumulated in the accident airplane make and model. The rear seat passenger in the Cessna airplane also held a student pilot certificate and had relinquished the controls to the flying student prior to the last takeoff. The flight instructor for the Piper airplane held instructor ratings in single engine, multiengine, and instrument airplanes. He also held a commercial pilot certificate with ratings for single engine, multiengine, and instrument airplanes. He was issued a second-class medical certificate on May 24, 1999, with a limitation to wear glasses. According to the Pilot/Operator Aircraft Accident Report, the flight instructor accumulated a total of 4,250 flight hours, of which 150 hours were accumulated in the same make and model as the accident airplane. He also reported having accumulated a total of 2,810 hours as a flight instructor, of which 120 hours were instructed in the same make and model as the accident airplane. The student, who was flying the Piper airplane at the time of the accident, had accumulated 22 total flight hours, of which approximately 3 hours were flown in the accident airplane make and model. WRECKAGE AND IMPACT INFORMATION According to witnesses, during the collision, the left wingtip from the high-wing Cessna was struck by the propeller and lower engine cowling of the overtaking low-wing Piper. The Cessna's left wing from the outboard section of the aileron separated during the collision. Numerous fragments from the wing were recovered from 33 degrees 50.65 minutes north latitude and 116 degrees 30.02 minutes west longitude, about 0.25 miles east of the intersection of Gene Autry Trail and Vista Chino. The Piper airplane sustained impact damage to its lower engine cowling, propeller, and propeller spinner. METEOROLOGICAL INFORMATION The Automatic Terminal Information Service (ATIS) information golf (1653) reported the wind from 220 at 5 knots; visibility 10 statute miles; clear sky; temperature 24 degrees Celsius; dew point 4 degrees Celsius; and an altimeter setting of 30.01 inches of mercury. According to the U.S. Naval Observatory's Astronomical Applications Department, sunset occurred at 1730, and the end of civil twilight occurred at 1755, at Palm Springs on the day of the accident. The use of a Safety Board Sun and Moon Information Program revealed that the sun would have been visible from the traffic pattern approximately 0.7 degrees above the horizon on a magnetic bearing of 242 degrees. With the Piper aircraft entering the traffic pattern on an approximate 30-degree entry angle, the sun would have been positioned slightly behind the right wing. With the Cessna climbing on the upwind leg of the traffic pattern, the sun would have been positioned almost directly behind them. AIRPORT INFORMATION The Palm Springs International Airport lies near the northwestern end of the Coachella Valley. The valley runs generally northwest-southeast, from a narrow area at the mouth of Banning Pass, widening toward the southeast to the Salton Sea. High terrain surrounds the valley in all other directions. Terrain prohibits circling or maneuvering to the west side of the airport. Visual procedures for all aircraft predominate, and instrument meteorological conditions are rare. Banning Pass is commonly used by visual flight rules (VFR) aircraft operating between PSP and the Los Angeles basin. Interstate Route 10 runs from the Banning Pass north of the airport then turns slightly to the southeast and parallels the runway complex. Interviews with air traffic controllers indicated that aircraft arriving from the Banning Pass area entering a 45-degree intercept of the downwind leg will appear to turn abeam the Desert Hot Springs residential development area. They also reported that some pilots familiar with the area will tend to turn early to follow the Gene Autry Trail, which results in a 30-degree intercept of the downwind leg. PSP has two parallel runways 13R/31L and 13L/31R. Runway 13R/31L is 8,500 feet long and 150 feet wide, and has displaced thresholds at each end. This runway is used virtually exclusively by air carrier operations. Runway 13L/31R is 4,952 feet long and 75 feet wide, with no displaced threshold. The airport elevation is 474 feet msl and the traffic pattern altitude for small aircraft is listed in the Airport Facility Directory as 1,474 feet msl (1,000 feet agl). AIR TRAFFIC CONTROL INFORMATION The PSP ATCT is a combined tower and radar approach control facility. The facility operates from 0600 to 2300. They are equipped with an Airport Surveillance Radar (ASR)-8 radar site, located approximately 4 miles east of the airport. There is a Terminal Radar Service Area (TRSA) surrounding the PSP airport. This is one of the last remaining TRSAs in the United States. At the time of the accident, due to technical difficulties with the ASR-8, PSP approach controllers were operating from a temporary military radar unit located on the east side of the airport. The military radar unit included its own radar sensor, which was utilized at the time of the accident. The military unit was equipped with a Conflict Alert program. The control tower cab was located on the southwest side of the airport, with an unobstructed view of the runways and the traffic pattern. The eastern mouth of the Banning Pass, along with Interstate 10, the Gene Autry Trail, and the Desert Hot Springs housing development, are all visible from the cab. The investigation team noted that in the afternoon hours, the high terrain to the west of the airport placed the control tower in shadow, while the majority of the traffic pattern remained in sunlight. Normally, the PSP local controllers are supplied with three D-BRITE (Digital Bright Radar Indicator Tower Equipment) displays, which were normally slaved to the Automated Radar Terminal System (ARTS). Due to the status of the ASR-8 radar, the D-BRITE displays in the tower cab were technically released to the Airways Facilities technicians. However, when the ASR-8 driving the D-BRITEs were operating, some controllers would utilize the displays as an additional aid. According to PSP Air Traffic Management, the local controller could "make an individual determination that the display is sufficient" to provide arrival information without verbal coordination. However, controllers were also instructed that "the D-BRITE shall not be used for radar separation or advisory services." On the day of the accident, due to the previous week's "unreliable" displays, the D-BRITE was completely off and there were pieces of paper covering the screens. ADDITIONAL INFORMATION The ATIS remarks section informed pilots that visual approaches in use landing and departing runways 31L and 31R. The ATIS also remarked that "Palm Springs TRSA services available on a limited workload and equipment permitting basis. No TRSA services available in Class D airspace..." Review of the Aeronautical Information Manual (AIM) revealed that the pilot responsibilities listed under 4-1-17 Terminal Radar Services for VFR Aircraft, indicate that "THESE SERVICES [Radar Services] ARE NOT TO BE INTERPRETED AS RELIEVING PILOTS OF THEIR RESPONSIBLITIES TO SEE AND AVOID OTHER TRAFFIC OPERATING IN BASIC VFR WEATHER CONDITIONS..." The AIM also prescribed procedures for operations at Airports with an Operating Control Tower (4-3-2). Under 4-3-2.d, the AIM indicates that "Many towers are equipped with a tower radar display. The radar uses are intended to enhance the effectiveness and efficiency of the local control, or tower position. They are not intended to provide radar services or benefits to pilots except as they may accrue through a more efficient tower operation." A note under that subpart indicates that "Pilots have complete discretion regarding acceptance of the suggested headings or directions and have the SOLE RESPOSIBILITY for seeing and avoiding other aircraft." The AIM also recommends that pilots enter the traffic pattern "in level flight, abeam the midpoint of the runway, at pattern altitude." Under the AIM section titled "Unexpected Maneuvers in the Airport Traffic Pattern," it is noted that "There have been several incidents in the vicinity of controlled airports that were caused primarily by aircraft executing unexpected maneuvers. ATC service is based upon observed or known traffic and airport conditions. Controllers establish the sequence of arriving and departing aircraft by requiring them to adjust flight as necessary to achieve proper spacing. These adjustments can only be based on observed traffic, accurate pilot reports, and anticipated aircraft maneuvers..." The AIM also recommends under section 4-3-23 Use of Aircraft Lights that "aircraft equipped with an anti-collision light system are required to be operated during all types of operations (day and night) except when the pilot-in-command determines that the anti-collision lights should be turned off when their light output during adverse meteorological conditions would constitute a hazard to safety." This section also reports that "The FAA has a voluntary pilot safety program, Operation Lights On, to enhance the see-and-avoid concept. Pilots are encouraged to turn on their landing lights during takeoff...[and] when operating within 10 miles of any airport." The flight instructor from the Piper aircraft reported in a written statement that they had their navigation, strobe, and landing lights on. It is unknown whether the Cessna aircraft had the anti-collision lights or landing light on.
the failure of both flight crews to see and avoid the other airplane while operating in the traffic pattern, which resulted in a mid-air collision. A contributing factor was the failure of the arriving aircraft to comply with air traffic control requests by not issuing a position report.
Source: NTSB Aviation Accident Database
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