Boeing 737 and Boeing C17 incident near Camp Springs, Maryland, April 18, 2011
On April 18, 2011 at about 9:06 pm local time, 2 aircraft, Boeing 737 and Boeing C17, were involved in the same incident near Camp Springs, Maryland (Andrews Air Force Base airport). The NTSB record does not give the injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The misapplication of wake turbulence and instrument flight rules (IFR) separation criteria by air traffic controllers.
The misapplication of wake turbulence and instrument flight rules (IFR) separation criteria by air traffic controllers.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- April 18, 2011 · about 9:06 pm local time
- Place
- Camp Springs, Maryland · Andrews Air Force Base · map
- Type
- Incident
- Injuries
- The NTSB record does not give the injuries.
- Weather
- visual conditions (good weather)
- Aircraft 1
- Boeing 737 · all 737s on the register
- Registration
- not recorded
- Damage
- Not recorded
- Flight
- Flight · military rules
- Aircraft 2
- Boeing C17 A
- Registration
- not recorded
- Damage
- Not recorded
- Flight
- Flight · military rules
The NTSB's narrative for the Boeing 737 final · quoted from the NTSB record
A Boeing 737 (B737) and a heavy Boeing C-17 were being provided radar vectors for instrument landing system approaches to the runway by a controller at the Potomac Terminal Radar Approach Control (TRACON) facility. The controller vectored the C-17 onto the base leg of the traffic pattern ahead of the B737 to join the localizer for the approach. At this point, the airplanes were separated by 4.45 miles on a converging course with a closure rate of 180 knots. The C-17 was subsequently vectored to join the localizer and cleared for the approach. The controller then issued a wake turbulence advisory to the B737 and informed the pilot he would be 4 miles in trail of the C-17. The pilot of the B737 acknowledged the advisory, but, at this point, the airplanes were 3.62 miles apart. The minimum required wake turbulence separation was 5 miles. Both airplanes were directed to contact the air traffic control tower local controller. As both airplanes reduced their speeds for landing during final approach, their separation was reduced to 2.81 miles. The minimum instrument flight rules separation was 3 miles. The local controller authorized the B737 to make "S" turns on final approach to increase separation; however, when the B737 was 2 miles from the landing threshold, the B737 pilot told the local controller, "it doesn't look like we're going to make this," since the C-17 was still conducting the landing roll on the runway. The B737 pilot was instructed to perform a go-around, entered a left downwind for the runway, and landed uneventfully. The TRACON controller responsible for the wake turbulence operational error reported after the incident that he confused the minimum wake turbulence separation requirements for a B737 following a C-17 with the requirement for a B757 following a B757. The B757 requirement was 4 miles. The TRACON controller had been involved in 4 other operational errors in the 4 years preceding this incident.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The NTSB's narrative for the Boeing C17 final · quoted from the NTSB record
A Boeing 737 (B737) and a heavy Boeing C-17 were being provided radar vectors for instrument landing system approaches to the runway by a controller at the Potomac Terminal Radar Approach Control (TRACON) facility. The controller vectored the C-17 onto the base leg of the traffic pattern ahead of the B737 to join the localizer for the approach. At this point, the airplanes were separated by 4.45 miles on a converging course with a closure rate of 180 knots. The C-17 was subsequently vectored to join the localizer and cleared for the approach. The controller then issued a wake turbulence advisory to the B737 and informed the pilot he would be 4 miles in trail of the C-17. The pilot of the B737 acknowledged the advisory, but, at this point, the airplanes were 3.62 miles apart. The minimum required wake turbulence separation was 5 miles. Both airplanes were directed to contact the air traffic control tower local controller. As both airplanes reduced their speeds for landing during final approach, their separation was reduced to 2.81 miles. The minimum instrument flight rules separation was 3 miles. The local controller authorized the B737 to make "S" turns on final approach to increase separation; however, when the B737 was 2 miles from the landing threshold, the B737 pilot told the local controller, "it doesn't look like we're going to make this," since the C-17 was still conducting the landing roll on the runway. The B737 pilot was instructed to perform a go-around, entered a left downwind for the runway, and landed uneventfully. The TRACON controller responsible for the wake turbulence operational error reported after the incident that he confused the minimum wake turbulence separation requirements for a B737 following a C-17 with the requirement for a B757 following a B757. The B757 requirement was 4 miles. The TRACON controller had been involved in 4 other operational errors in the 4 years preceding this incident.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record for the Boeing 737 from the NTSB's investigation tables, in plain English
What happened, in order
- Air traffic event during approach (IFR final approach)
- Near midair/TCAS alert/loss of separation during approach (IFR final approach) defining event
The NTSB's findings
- cause Personnel issues › Action/decision › Action › Incorrect action selection › ATC personnel
- cause Personnel issues › Action/decision › Info processing/decision › Decision making/judgment › ATC personnel
The aircraft
- Landing gear: retractable
- Operator: United States Air Force
The flight
- Departed from: Unknown
- Destination: ADW Camp Springs MD
- Flight plan: IFR
- Runway 19L, 9,755 ft by 150 ft
Weather at the time
- Light: daylight
- Wind: from 180° at 14 knots
- Visibility: 10 statute miles
- Sky: a few clouds at 14,000 ft
- Temperature: 93°F (34°C), dew point 45°F (7°C)
- Altimeter: 29.88 inHg
- Observation at 8:55 pm from ADW
The factual record for the Boeing C17 from the NTSB's investigation tables, in plain English
What happened, in order
- Air traffic event during approach (IFR final approach)
- Near midair/TCAS alert/loss of separation during approach (IFR final approach) defining event
The NTSB's findings
- cause Personnel issues › Action/decision › Action › Incorrect action performance › ATC personnel
- cause Personnel issues › Action/decision › Info processing/decision › Decision making/judgment › ATC personnel
The aircraft
- Landing gear: retractable
- Operator: United States Air Force
The flight
- Departed from: Unknown
- Destination: ADW Camp Springs MD
- Flight plan: IFR
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.