Individually Owned: 150,657
Corporate Owned: 137,281
San Francisco Intl Airport
Aircraft Accident/Incident Report
San Francisco, California 94128
Saturday, May 26, 2007 13:36 PDT
NTSB Narrative Summary Released at Completion of Accident
On May 26, 2007, at 1336 Pacific daylight time, Republic Airlines flight 4912 (RPA4912), an Embraer 170 regional jet, and Skywest Airlines flight 5741 (SKW5741), an Embraer Brasilia turboprop, nearly collided in the intersection of runway 1L and runway 28R at San Francisco International Airport, San Francisco, California. Both aircraft were operating as scheduled passenger flights under 14 CFR part 121 and were operating on instrument flight plans. There were no reported injuries to occupants and no reported damage to either aircraft.
SKW5741 was arriving at SFO after a flight from Modesto, California. The aircraft was cleared for a visual approach by Northern California Terminal Radar Approach Control (NCT) and transferred to SFO tower. The crew contacted the SFO local controller at 1332:29, reporting that they were six miles out on the BRIJJ visual approach. The local controller acknowledged, issued a wake turbulence advisory for a Boeing 757 landing on runway 28L, and cleared SKW5741 to land on runway 28R. According to NCT radar data, the aircraft crossed the runway threshold at 1335:13.
RPA4912 (radio callsign "Brickyard 4912"), taxied to runway 1L and was instructed to taxi onto the runway to hold at 1333:36. RPA4912 was cleared for takeoff at 1335:12. The crew acknowledged.
At 1335:40, during a transmission to an uninvolved aircraft by the local controller, an aural AMASS warning is audible in the background. At 1335:44, the local controller begins attempting to instruct SKW5741 to stop, transmitting, "uh, Skywest HOLD HOLD HOLD".
According to controllers' written statements, SKW5741 came to a stop in the intersection of runways 1L and 28R. RPA4912 lifted off and overflew SKW5741. The initial FAA tower report estimated the aircraft missed colliding by 300 feet. However, the Skywest crew estimated the distance as 30 to 50 feet and the crew of RPA4912 estimated 150 feet. They characterized their estimate as a "guess," noting that they could not actually see the Brasilia as they passed over the top of the aircraft.
SFO ATCT is equipped with an Airport Movement Area Safety System (AMASS) that uses radar to track aircraft on and near the airport surface, providing conflict detection and aircraft location information to controllers. The system is able to detect conflicts between aircraft using the same runway, and, following a software modification that was installed on February 17, 2007, the system is also able to detect conflicts between aircraft using intersecting runways.
SKW5741's approach was tracked by NCT's ASR-9 terminal radar system located at Oakland International Airport, approximately 8 miles north of SFO. The Oakland radar system does not provide surface coverage at SFO, but it did detect RPA4912 climbing off the airport immediately after the incident. Comparison of the NCT radar time with the AMASS radar time indicated that the AMASS clock was about 15 to 16 seconds fast in relation to the NCT clock. The NCT clock is set and checked every shift, but the AMASS clock time is derived from the internal clock of the computer running AMASS and is more subject to error. Therefore, this report will consider the ARTS clock as authoritative and AMASS times will be corrected accordingly.
The AMASS system recorded data for both RPA4912 and SKW5741, detecting the conflict and alerting controllers at 1335:40. The AMASS targets for the two aircraft merged in the runway intersection at 1335:55. RPA1912 first appears on the OAK ASR-9 just south of taxiway V at 1335:59, climbing through 200 feet.
NTSB Probable Cause Narrative
Failure of SFO tower local controller to provide adequate separation between two aircraft departing intersecting runways.
Event Information
| Type of Event | Incident |
| Event Date | 5/26/2007 |
| Event Day of the Week | Saturday |
| Time of Event | 1336 |
| Event Time Zone | Pacific Daylight Time |
| Event City | San Francisco |
| Event State | CALIFORNIA |
| Event Country | -- |
| Zipcode of the event site | 94128 |
| Event Date Year | 2007 |
| Event Date Month | 5 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 373701N |
| Event Location Longitude | 1222300W |
| Event Location Airport | SAN FRANCISCO INTL |
| Event Location Nearest Airport ID | SFO |
| Indicates whether the acc/inc occurred off or on an airport | On Airport |
| Distance from airport in statute miles | 0 |
| Degrees magnetic from airport | -- |
| Airport Elevation | 11 |
| Weather Briefing Completeness | -- |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | |
| Direction of event from weather observation facility (degrees) | -- |
| Weather Observation Facility ID | SFO |
| Elevation of weather observation facility | -- |
| Distance of event from weather observation facility (units?) | -- |
| Time Zone of the weather observation | -- |
| Lighting Conditions | -- |
| Lowest Ceiling Height | -- |
| Lowest Non-Ceiling Height | 1100 |
| Sky/Lowest/Cloud Conditions | Few |
| Sky Condition for Lowest Ceiling | -- |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | 10 |
| Air Temperature at event time (in degrees celsius) | 18 |
| Dew Point at event time (in degress fahrenheit) | 10 |
| Wind Direction (degrees magnetic) | 320 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 13 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | -- |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | 29.95 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | -- |
| Event Highest Injury | None |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | -- |
| Injury Total Minor | -- |
| Injury Total None | 92 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 22757 |
| NTSB Notification Source | FAA |
| NTSB Notification Date | May 26 2007 12:00AM |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | DMS |
| Date of most recent change to record | Nov 30 2007 3:42PM |
| User who most recently changed record | NTSB\lema |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
||
|---|---|---|
Aircraft #1 |
Aircraft #2 |
|
| Aircraft Registration Number | -- | -- |
| NTSB Number | OPS07IA004A | OPS07IA004B |
| Missing Aircraft Indicator | -- | -- |
| Federal Aviation Reg. Part | -- | -- |
| Type of Flight Plan filed | IFR | -- |
| Flight plan Was Activated? | Yes | -- |
| Damage | None | None |
| Aircraft Fire | -- | -- |
| Aircraft Explosion | -- | -- |
| Aircraft Manufacturer's Full Name | Embraer | Embraer |
| Aircraft Model | 170 | 120 |
| Aircraft Series Identifier | -- | -- |
| Aircraft Serial Number | -- | N232SW |
| Certified Max Gross Weight | -- | -- |
| Aircraft Category | Airplane | Airplane |
| Aircraft Registration Class | -- | -- |
| Aircraft is a homebuilt? | No | No |
| Flight Crew Seats | -- | -- |
| Cabin Crew Seats | -- | -- |
| Passenger Seats | -- | -- |
| Total number of seats on the aircraft | -- | -- |
| Number of Engines | -- | -- |
| Fixed gear or retractable gear | Fixed | Fixed |
| Aircraft, Type of Last Inspection | -- | -- |
| Date of Last Inspection | -- | -- |
| Airframe hours since last inspection | -- | -- |
| Airframe Hours | -- | -- |
| ELT Installed | -- | -- |
| ELT Activated | -- | -- |
| ELT Aided Location of Event Site | -- | -- |
| ELT Type | -- | -- |
| Aircraft Owner Name | -- | -- |
| Aircraft Owner Street Address | -- | -- |
| Aircraft Owner City | -- | -- |
| Aircraft Owner State | -- | -- |
| Aircraft Owner Country | -- | -- |
| Aircraft Owner Zipcode | -- | -- |
| Operator is an individual? | No | -- |
| Operator Name | -- | -- |
| Operator Same as Owner? | No | -- |
| Operator Is Doing Business As | -- | -- |
| Operator Address Same as Owner? | No | -- |
| Operator Street Address | -- | -- |
| Operator City | -- | -- |
| Operator State | -- | -- |
| Operator Country | -- | -- |
| Operator Zip code | -- | -- |
| Operator Code | REPA | NCJL |
| Owner has at least one certificate | -- | -- |
| Other Operator of large aircraft? | -- | -- |
| Certified for Part 133 or 137 Operation | -- | -- |
| Operator Certificate Number | -- | -- |
| Indicates whether an air carrier operation was scheduled or not | Scheduled | Scheduled |
| Indicates Domestic or International Flight | Domestic | Domestic |
| Operator carrying Pax/Cargo/Mail | Passenger Only | Passenger Only |
| Type of Flying (Per_Bus / Primary) | -- | -- |
| Second Pilot on Board | Yes | -- |
| Departure Point Same as Event | Yes | No |
| Departure Airport Code | SFO | -- |
| Departure City | San Francisco | -- |
| Departure State | CA | -- |
| Departure Country | USA | -- |
| Departure Time | 1335 | -- |
| Departure Time Zone | PDT | -- |
| Destination Same as Local Flt | -- | -- |
| Destination Airport Code | LAX | -- |
| Destination City | Los Angeles | -- |
| Destination State | CA | -- |
| Destination Country | USA | -- |
| Specific Phase of Flight | Takeoff | Landing - roll |
| Report sent to ICAO? | -- | -- |
| Evacuation occurred | -- | -- |
| Date of most recent change to record | Nov 19 2007 3:06PM | Nov 19 2007 3:06PM |
| User who most recently changed record | ROWS | ROWS |
| Since inspection or accident | -- | -- |
| Event Location Runway Number and Location | -- | -- |
| Runway Length | -- | -- |
| Runway Width | -- | -- |
| Sight Seeing flight | No | -- |
| Air Medical Flight | No | -- |
| Medical Flight | -- | -- |