Editor's Note: The National Transportation Safety Board has issued its latest update on the board's investigation of the September 29 midair collision over the Amazon Jungle of a Gol Airlines Boeing 737 and an Embraer Legacy 600 business jet.

In the update, which follows below, the NTSB says both the Legacy and the airliner were cleared to FL370. According to the flight plan filed by the Legacy's pilots, however, the bizjet was supposed to descend to FL360, and then climb to FL380, before it crossed paths with the Brazilian plane. The pilots did not request either altitude change... and ATC did not direct the pilots to move to a different altitude.

The board also found that communications between Brazilian controllers and the Legacy became increasingly erratic; at one point, the Embraer's pilots tried to contact ATC 12 times, without success. Controllers also stopped receiving the Legacy's transponder code before the collision.

The government of Brazil has asked the National Transportation Safety Board to disseminate the following factual information on the progress of its investigation into a midair collision over the Brazilian Amazon jungle on September 29, 2006, between a Boeing 737-800 (PR-GTD) operated by Gol Airlines of Brazil, and an Embraer Legacy 600 business jet (N600XL) owned and operated by Excelaire of Long Island, New York.

The accident investigation is being conducted under the authority of the Brazilian Aeronautical Accident Prevention and Investigation Center (DIPAA). Under the provisions of ICAO Annex 13, the United States, as state of registry and operator of the Excelaire Legacy, and state of manufacture of the Boeing 737 and Honeywell avionics equipment in both airplanes, has provided an accredited representative and technical advisors for the investigation. The U.S. team includes the accredited representative from the major aviation accident investigations division of the NTSB, as well as technical advisors in operations, systems, air traffic control, flight recorders, and aircraft performance. Additional technical advisors from Boeing, Excelaire, Honeywell, and FAA have also been included.

The accident occurred about 4:57 pm Brasilia standard time.

The Boeing 737 was destroyed by in-flight breakup and impact forces; all 154 occupants were fatally injured. The wreckage of the 737 was located in remote jungle terrain with very difficult access. Brazilian military search and rescue personnel have located the flight recorders and all significant portions of the wreckage except the outer portion of the left wing. The Legacy N600XL experienced damage to its left wing and left horizontal stabilizer and performed an emergency landing at the Cachimbo Air Base, approximately 60 miles northwest of the collision site. There was no further damage to the airplane, and the 2 crew members and 5 passengers were not injured. The airplane remained at the base and significant components have been tested and recovered from the aircraft.

Visual meteorological conditions prevailed in the area of the accident. Both aircraft were operating on instrument flight rules, on instrument flight plans and clearances.

The Boeing 737 was a scheduled domestic air carrier flight enroute from the Eduardo Gomes International Airport, Manaus, Brazil; to the Presidente Juscelino Kubitschek Airport, Brasilia. The Legacy N600XL was enroute from the Prof. Urbano Ernesto Stumpf airport, San Jose dos Campos, Brazil (SBSJ), to a stopover in Manaus, and eventually enroute back to the U.S. This was Excelaire's initial flight with this aircraft, taking delivery from the Embraer factory and a planned flight to Excelaire's home base in New York.

History of flights:

The Legacy N600XL departed SBSJ at about 2:51 pm. The filed flight plan included a routing via the OREN departure procedure to Pocos beacon, then airway UW2 to Brasilia VOR (BRS), airway UZ6 to Manaus. The cruise altitude was filed as FL370, with a planned change to FL360 at BRS, and to FL380 at the TERES navigational fix, approximately 282 miles north of BRS.

After takeoff, N600XL was issued a number of interim altitudes during climb, all of which were read back. The flight was cleared to proceed direct to Araxa VOR (on airway UW2), and at 3:11 pm was cleared to climb to FL370. At 3:33 pm, the airplane leveled at FL370.

At 3:35 pm, the Boeing 737 departed Eduardo Gomes airport, requesting FL370 as a cruise altitude, and a routing via UZ6 to BRS. The airplane reached FL370 at 3:58 pm. There were no anomalies in communications with or radar surveillance of the Boeing 737 throughout the flight.

At 3:51 pm, an air traffic controller in the Brasilia ACC (CINDACTA 1) instructed N600XL to change frequencies to the next controller's sector. The crew of N600XL reported in on the assigned frequency that the flight was level at FL370. ATC acknowledged and instructed the crew to "ident" (flash their transponder). Radar indicates that the ident was observed. This was the last two-way communication between N600XL and ATC. At this time the airplane was approximately 40 nautical miles south of BRS.

At 3:56pm the Legacy N600XL passed BRS level at FL370. There is no record of a request from N600XL to the control agencies to conduct a change of altitude, after reaching flight level 370. The airplane made calls, but there is no communication in which it requested a change of flight level. There is also no record of any instruction from air traffic controllers at Brasilia Center to the aircraft, directing a change of altitude.

When the airplane was about 30 miles north-northwest of BRS, at 4:02 pm, the transponder of N600XL was no longer being received by ATC radar. A transponder reports a unique code, aiding radar identification, and provides an accurate indication of the airplane's altitude. Additionally, the transponder is a required component for the operation of Traffic Collision Avoidance System equipment, commonly called the TCAS system.

Between 3:51 pm and 4:26 pm, there were no attempts to establish radio communications from either the crew of N600XL or ATC. At 4:26 pm the CINDACTA 1 controller made a "blind call" to N600XL. Subsequently until 4:53 pm, the controller made an additional 6 radio calls attempting to establish contact. The 4:53 call instructed the crew to change to frequencies 123.32 or 126.45. No replies were received.

There is no indication that the crew of N600XL performed any abnormal maneuvers during the flight. Flight Data Recorder information indicates that the airplane was level at FL370, on course along UZ6, and at a steady speed, until the collision. Primary (non-transponder) radar returns were received corresponding to the estimated position of N600XL until about 4:30 pm. For 2 minutes, no returns were received, then returns reappeared until 4:38 pm. After that time, radar returns were sporadic.

Beginning at 4:48 pm, the crew of N600XL made a series of 12 radio calls to ATC attempting to make contact. At 4:53, the crew heard the call instructing them to change frequencies, but the pilot did not understand all of the digits, and requested a repeat. No reply from ATC was received. The pilot made 7 more attempts to establish contact.

At 4:56:54 pm the collision occurred at FL370, at a point about 460 nautical miles north-northwest of BRS, on airway UZ6.

There was no indication of any TCAS alert on board either airplane, no evidence of pre-collision visual acquisition by any flight crew member on either aircraft, and no evidence of evasive action by either crew.

Wreckage and damage examination indicates that it is likely the left winglet of the Legacy (which includes a metal spar) contacted the left wing leading edge of the Boeing 737. The impact resulted in damage to a major portion of the left wing structure and lower skin, ultimately rendering the 737 uncontrollable. Flight recorder information ceased at an approximate altitude of 7,887 feet.

After the collision, the crew of N600XL made numerous further calls to ATC declaring an emergency and their intent to make a landing at the Cachimbo air base.

At 5:02 pm, the transponder returns from N600XL were received by ATC.

At 5:13 pm, an uninvolved flight crew assisted in relaying communications between N600XL and ATC until the airplane established communication with Cachimbo tower.

Investigative activities completed to date:

Flight recorders from both airplanes were recovered and downloaded at the Transportation Safety Board of Canada (TSB) laboratories. Transcriptions of the cockpit voice recorders (CVRs) were prepared (the transcript of the Legacy's CVR was produced at the NTSB's laboratory in Washington, D.C.) and data from flight data recorders obtained.

Initial interviews and medical examinations were conducted with the crew of the Legacy. Air Traffic Control data was gathered. Preliminary tests of the avionics equipment on the Legacy were performed. Wreckage of the 737 was examined.

Future investigative activity:

Additional investigative work will include laboratory tests of the avionics components removed from the Legacy, an examination of the operating procedures of the avionics, interviews with ATC personnel, examination of ATC practices and comparison between Brazilian and FAA procedures, a technical examination of ATC communication and surveillance systems, and further examination of the training provided to the operators.

The Investigator in Charge estimates a 10-month timeline for the investigation. The first phase, data gathering is estimated to take approximately 45 days, although some further data gathering remains to be completed. Analysis of the data is estimated to take 90 days followed by a preliminary report with conclusions 120 days afterward.

Preparation of the final report and review by involved parties and States is estimated at a further 30 days each.

FMI: www.ntsb.gov