Aeroperú Flight 603

Aeroperú Flight 603 was a scheduled flight from Jorge Chávez International Airport in Lima, Peru (SPIM), to Comodoro Arturo Merino Benítez International Airport in Santiago, Chile (SCEL), which crashed on October 2, 1996.

The pilots struggled to navigate the aircraft after the failure of all the plane's instruments. With the pilots unaware of their true altitude, the plane's wing hit the water and it crashed shortly afterward. The cause of the instrument failure was a maintenance worker's failure to remove tape covering the static ports necessary to provide correct instrument data to the cockpit.

Overview
On October 2, 1996, shortly after takeoff just past midnight, the Boeing 757 airliner crew discovered that their basic flight instruments were behaving erratically and reported receiving contradictory serial emergency messages from the onboard computer, such as rudder ratio, mach speed trim, overspeed, underspeed and flying too low. The crew declared an emergency and requested an immediate return to the airport.

Faced with the lack of reliable basic flight instruments, constant contradictory warnings from the aircraft's flight computer (some of which were valid and some of which were not), and believing that they were at a safe altitude, pilot Eric Schreiber Ladrón de Guevara and copilot David Fernández Revoredo decided to cautiously begin descent for the approach to the airport. Since the flight was at night over water, no visual references could be made to convey to the pilots their true altitude or aid the pilots in the descent. Also, as a consequence of the pilots' inability to precisely monitor the aircraft's airspeed or vertical speed, they experienced multiple stalls, resulting in rapid loss of altitude with no corresponding change on the altimeter. While the altimeter indicated an altitude of approximately 9,700 feet, the aircraft's true altitude was in fact much lower.

The air traffic controller had a Boeing 707 take off to help guide the 757 back to land. Before the 707 could reach the 757, the 757's wingtip struck the water approximately twenty-five minutes after emergency declaration, making the pilots realize the true altitude of the airliner; the pilots struggled with the controls and managed to get airborne again for twenty seconds, but the aircraft crashed inverted into the water. All nine crew members and sixty-one passengers died. The pilots, distracted by the conflicting warnings, did not notice the radar altimeter after passing through 2,500 feet, according to the accident report.

After the crash recovery crews found nine bodies floating; the rest of the bodies sank with the airliner.

Passengers and crew
Half of the passengers on Flight 603 were Chileans returning to Chile.

Of the passengers, 21 originated from Miami; all of the originating passengers were Chilean.

Reporting
Some very early reports initially stated that the crashed flight flew on a New York City to Lima route; the agencies later corrected reports, stating that the flight was flying from Lima to Santiago.

Investigation
The Commission of Accident Investigations (CAI) of the Director General of Air Transport (DGAT) of Peru wrote the final accident report.

The Peruvian accident investigator, Guido Fernández Lañas, was the uncle of the co-pilot, David Fernández, but, despite originally holding some reservations about the potential conflict of interest, the National Transportation Safety Board -appointed investigator, Richard Rodriguez, determined that he could properly investigate the accident.

The Peruvian Navy collected the floating wreckage. After the Peruvian authorities asked for assistance, the United States Navy provided equipment to locate the underwater wreckage and black boxes of the Boeing 757.

Later investigation into the accident revealed that masking tape was accidentally left over some or all of the static ports (on the underside of the fuselage) after the aircraft was cleaned, eventually leading to the crash. Employee Eleuterio Chacaliaza left the tape on by mistake.

The static ports are critical to the operation of virtually all of those flight instruments that provide basic aerodynamic data such as airspeed, altitude and vertical speed, not only to the pilots but also to the aircraft's computers, which provide additional functions such as warnings when flight characteristics approach dangerous levels. The blockage of all of the static ports is one of the few common-failure modes resulting in total failure of multiple basic flight instruments and as such is regarded as one of the most serious faults that can occur within the avionics systems.

The design of the aircraft did not incorporate a system of maintenance covers for the static ports. Such covers are commonly employed in aviation for blocking access to critical components when the aircraft is not in operation and are generally a bright color and carry flags (which may have "remove before flight" markings). Instead, the design of the aircraft and the relevant maintenance procedure called for the use of adhesive tape to cover the ports.

As a result of the blocked static ports, the basic flight instruments relayed false airspeed, altitude and vertical speed data. Because the failure was not in any of the instruments but rather in a common supporting system, thereby defeating redundancy, the altimeter also relayed the false altitude information to the Air Traffic Controller, who was attempting to provide the pilots with basic flight data. This led to extreme confusion in the cockpit as the pilots were provided with some data (altitude) which seemed to correlate correctly with instrument data (altimeter) while the other data provided by ATC (approximate airspeed) did not agree. Although the pilots were quite cognizant of the possibility that all of the flight instruments were providing inaccurate data, the correlation between the altitude data given by ATC and that on the altimeter likely further compounded the confusion. Also contributing to their difficulty were the numerous cockpit alarms that the computer system generated, which conflicted both with each other and with the instruments. This lack of situational awareness can be seen in the CVR transcript. The fact that the flight took place at night and over water, thus not giving the pilots any visual references, was also a major factor.

Legal settlement
In November 1996, Mike Eidson, a Miami attorney from Colson Hicks Eidson, said in an interview that many of the passengers survived the initial impact and drowned afterwards. Eidson represented 41 passengers and crew in a lawsuit contending that the aircraft's manufacturer, Boeing, bore responsibility for the disaster, as the company had to foresee the misuse of its products. The suit was filed against Boeing in federal court in Miami in May, 1997. According to the complaint, the control panel errors were caused by careless maintenance by Aeroperú and negligence and defective design by Boeing. Boeing argued that it was not at fault, and that responsibility for the accident lay with the aircraft's pilot for not finding the tape. Richard Rodriguez of the NTSB said that it was understandable that Schreiber did not find the tape because the maintenance worker used duct tape instead of the bright tape that he was supposed to use. In addition, Rodriguez said that the pitot-static ports were high above the ground. Therefore Schreiber did not see the tape against the fuselage. After extensive litigation, the parties agreed to transfer the case against Boeing and Aeroperú to an international arbitration in Santiago, Chile, for a determination of the damages. The defendants agreed not to contest liability in Chile.

On December 13, 1999, family members of the flight's passengers received one of the largest cash awards stemming from an aviation accident outside the United States aboard a non-U.S. carrier. The episode "Flying Blind" from Mayday (Air Crash Investigation, Air Emergency) stated that the manner of the crash resulting in the passengers' drowning was responsible for the large settlements.

After the accident, Aeroperú changed the number of its evening Miami-Lima-Santiago Boeing 757 service to Flight 691. The Flight 603 incident contributed to the eventual demise of Aeroperú, which was already plagued with financial and management difficulties. The airline folded in 1999.

Peruvian justice sentenced Chacaliaza for negligent homicide; it did not sentence any other staff members of the airline. Guido Fernández criticized the move; he argued that Chacaliaza, who was relatively uneducated, had little understanding of what he did, and that his supervisors had more responsibility.

Dramatization
The accident was featured in the episode "Flying Blind" from Mayday (Air Crash Investigation, Air Emergency). The cockpit voice recording of the incident became part of the script of a play called Charlie Victor Romeo.