Individually Owned: 150,657
Corporate Owned: 137,281
Andrews Air Force Base Airport
Aircraft Accident/Incident Report
Camp Springs, Maryland 20762
Monday, April 18, 2011 17:06 EDT
NTSB Narrative Summary Released at Completion of Accident
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.
NTSB Probable Cause Narrative
The misapplication of wake turbulence and instrument flight rules (IFR) separation criteria by air traffic controllers.
Event Information
| Type of Event | Incident |
| Event Date | 4/18/2011 |
| Event Day of the Week | Monday |
| Time of Event | 1706 |
| Event Time Zone | Eastern Daylight Time |
| Event City | Camp Springs |
| Event State | MARYLAND |
| Event Country | -- |
| Zipcode of the event site | 20762 |
| Event Date Year | 2011 |
| Event Date Month | 4 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | -- |
| Event Location Longitude | -- |
| Event Location Airport | Andrews Air Force Base |
| Event Location Nearest Airport ID | ADW |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | 6 |
| Degrees magnetic from airport | -- |
| Airport Elevation | 280 |
| Weather Briefing Completeness | -- |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 1655 Eastern Daylight Time |
| Direction of event from weather observation facility (degrees) | -- |
| Weather Observation Facility ID | ADW |
| Elevation of weather observation facility | 280 |
| Distance of event from weather observation facility (units?) | -- |
| Time Zone of the weather observation | EDT |
| Lighting Conditions | Day |
| Lowest Ceiling Height | -- |
| Lowest Non-Ceiling Height | 14000 |
| Sky/Lowest/Cloud Conditions | Few |
| Sky Condition for Lowest Ceiling | None |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | 10 |
| Air Temperature at event time (in degrees celsius) | 34 |
| Dew Point at event time (in degress fahrenheit) | 7 |
| Wind Direction (degrees magnetic) | 180 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 14 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | -- |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | 29.89 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | -- |
| Event Highest Injury | -- |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | -- |
| Injury Total Minor | -- |
| Injury Total None | -- |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 29170 |
| NTSB Notification Source | FAA |
| NTSB Notification Date | -- |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | -- |
| Date of most recent change to record | Dec 22 2011 9:50AM |
| User who most recently changed record | andj |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
||
|---|---|---|
Aircraft #1 |
Aircraft #2 |
|
| Aircraft Registration Number | -- | -- |
| NTSB Number | OPS11IA499A | OPS11IA499B |
| Missing Aircraft Indicator | -- | -- |
| Federal Aviation Reg. Part | -- | -- |
| Type of Flight Plan filed | IFR | IFR |
| Flight plan Was Activated? | Yes | Yes |
| Damage | None | None |
| Aircraft Fire | None | None |
| Aircraft Explosion | None | None |
| Aircraft Manufacturer's Full Name | BOEING | BOEING |
| Aircraft Model | 737 | C17 |
| Aircraft Series Identifier | -- | A |
| Aircraft Serial Number | -- | -- |
| Certified Max Gross Weight | -- | -- |
| Aircraft Category | Airplane | Airplane |
| Aircraft Registration Class | -- | -- |
| Aircraft is a homebuilt? | No | -- |
| Flight Crew Seats | -- | -- |
| Cabin Crew Seats | -- | -- |
| Passenger Seats | -- | -- |
| Total number of seats on the aircraft | -- | -- |
| Number of Engines | 2 | 4 |
| Fixed gear or retractable gear | Retractable | Retractable |
| Aircraft, Type of Last Inspection | -- | -- |
| Date of Last Inspection | -- | -- |
| Airframe hours since last inspection | -- | -- |
| Airframe Hours | -- | -- |
| ELT Installed | Unknown | Unknown |
| ELT Activated | Unknown | Unknown |
| ELT Aided Location of Event Site | Unknown | Unknown |
| ELT Type | Unknown | Unknown |
| Aircraft Owner Name | -- | -- |
| Aircraft Owner Street Address | -- | -- |
| Aircraft Owner City | -- | -- |
| Aircraft Owner State | -- | -- |
| Aircraft Owner Country | USA | USA |
| Aircraft Owner Zipcode | -- | -- |
| Operator is an individual? | No | No |
| Operator Name | -- | -- |
| Operator Same as Owner? | Yes | Yes |
| Operator Is Doing Business As | -- | -- |
| Operator Address Same as Owner? | No | No |
| Operator Street Address | -- | -- |
| Operator City | -- | -- |
| Operator State | -- | -- |
| Operator Country | USA | USA |
| Operator Zip code | -- | -- |
| Operator Code | -- | -- |
| Owner has at least one certificate | None | None |
| Other Operator of large aircraft? | No | No |
| Certified for Part 133 or 137 Operation | -- | -- |
| Operator Certificate Number | -- | -- |
| Indicates whether an air carrier operation was scheduled or not | -- | -- |
| Indicates Domestic or International Flight | -- | -- |
| Operator carrying Pax/Cargo/Mail | -- | -- |
| Type of Flying (Per_Bus / Primary) | -- | -- |
| Second Pilot on Board | -- | -- |
| Departure Point Same as Event | No | No |
| Departure Airport Code | -- | -- |
| Departure City | Unknown | Unknown |
| Departure State | -- | -- |
| Departure Country | USA | USA |
| Departure Time | -- | -- |
| Departure Time Zone | -- | -- |
| Destination Same as Local Flt | -- | -- |
| Destination Airport Code | ADW | ADW |
| Destination City | Camp Springs | Camp Springs |
| Destination State | MD | MD |
| Destination Country | USA | USA |
| Specific Phase of Flight | -- | -- |
| Report sent to ICAO? | -- | -- |
| Evacuation occurred | -- | -- |
| Date of most recent change to record | Oct 12 2011 3:34PM | Oct 12 2011 3:34PM |
| User who most recently changed record | bard | bard |
| Since inspection or accident | -- | -- |
| Event Location Runway Number and Location | 19L | N/A |
| Runway Length | 9755 | -- |
| Runway Width | 150 | -- |
| Sight Seeing flight | -- | -- |
| Air Medical Flight | -- | -- |
| Medical Flight | -- | -- |