Everyone knows that flying into hurricanes is dangerous work. The NOAA Hurricane Hunter aircraft have flown a number of dangerous flights over the years, most recently in Hurricane Felix
on September 2 this year. NOAA P-3 aircraft N42RF (affectionately called Kermit), penetrated a rapidly intensifying Hurricane Felix as it approached Category 5 intensity. The aircraft hit four G's of acceleration in both the up and down directions in Felix's eyewall. Regulations require a flight to be aborted at that level of turbulence, and Kermit returned to base. A detailed inspection of the aircraft the next day revealed no damage, and Kermit returned to service for the remainder of hurricane season.Figure 1.
A NOAA P-3 refuels in Cold Bay, Alaska (left) on its way to the Aleutian Islands to fly a mission in the 1987 Alaska Storms Program. Right: The two NOAA P-3's get de-iced at Brunswick Naval Air Station, Maine, as they prepare for a mission into a 'Noreaster during the Experiment on Rapidly Intensifying Cyclones over the Atlantic (ERICA) in 1989. Both photos taken by yours truly.
What is less appreciated is that these aircraft fly research missions into dangerous weather conditions year-round and world-wide, and some of the most dangerous flights have occurred far from the tropics. Earlier this year, Kermit experienced perhaps the most dangerous flight of its 31-year career. On February 9, the aircraft flew into an intense winter storm 500 miles east of Newfoundland. The mission was part of the Ocean Winds project
, a study designed to test the accuracy of QuikSCAT satellite wind estimates in regions of high wind and heavy rain. Flying at 3,000 feet, the aircraft sampled the surface winds with its SFMR (Step Frequency Microwave Radiometer) and dropsondes. The flights were timed to coincide with an overhead pass of the QuikSCAT satellite, which also measured winds at the ocean surface. It was a bit of a rough ride, since the storm packed winds of 100-110 mph at flight level. Sea spray kicked up by the powerful winds reached all the way to flight level, coating the windshield with a thick white coating of salt. The windshield washer failed, leaving the windshield partially opaque. It was an unusually dry winter storm, and the rain showers needed to rinse the windshield clean were difficult to find.Figure 2.
QuikSCAT wind profile of the ocean surface at 21:22 GMT February 9, 2007, just before Kermit headed back to St. John's, Newfoundland.
After a successful 4-hour flight, the aircraft dropped its final dropsonde, and turned north to complete its final sampling run. Suddenly, crew members observed flames coming from the #3 engine, accompanied by an audible popping sound. "Fire on #3, flames, flames, flames!" came the cry over the on-board intercom system. The pilots and flight engineers immediately began an emergency shut down of the #3 engine. As they worked to shut down the engine, the ominous call, "Fire on #4!" came over the intercom. The pilot immediately began an emergency shut down of the #4 engine. With both engines on the right wing now shut down, the pilot cautiously ramped up power on the two engines on the left wing, turned the aircraft towards home base in St. Johns, Newfoundland, and attempted to climb. However, the aircraft was not able to climb on just two engines, and the pilot was forced to begin a gradual descent to 2600 feet. The pilot notified the crew to review their ditching placards, and word was send to air traffic control informing them of the emergency. Three tense minutes passed, as the crew attempted to figure out what had caused the multiple engine failures. Speculation centered on the unusually heavy accumulation of salt on the aircraft--but excessive salt had never been implicated in engine failures before. Then, the words they all dreaded, "Fire on #1!" burst out over the intercom. The flight engineer immediately pulled the emergency shutdown handle for the #1 engine, and Kermit began a 700 foot per minute descent towards the turbulent sea below.
The crew donned survival suits as the pilot issued a May-day distress call and prepared to ditch the aircraft. Beneath them, hurricane force winds blew over the night-shrouded North Atlantic waters. With waves easily reaching 20 feet, water temperatures near freezing, and 500 miles out at sea at night, prospects for survival were dim. Four minutes remained to restart one of the flamed-out engines, and the pilot called for an immediate restart of the #1 engine. As the flight engineer worked to comply, Kermit passed through a brief rain shower that washed considerable salt from the aircraft. The attempt to restart the #1 engine succeeded, and Kermit pulled out of its descent just 800 feet above the waves--one minute from impact.
The crew now worked to restart the failed #3 and #4 engines, while the plane slowly climbed away from the ocean surface. As they headed towards Newfoundland, the Canadian Air Force launched a search and rescue C-130 aircraft from Nova Scotia to intercept Kermit. Crews on the Hibernia and Terra Nova oil rigs located east of Newfoundland were alerted of the emergency, and stood by to help if necessary. Kermit's navigator continuously plotted vectors to the oil rigs at they flew home, in case a ditch near one of the rigs became necessary.
As they continued westward, the crew successfully restarted both the #3 and #4 engines, but at reduced power. Kermit climbed to a more comfortable altitude of 14,000 feet and made it uneventfully back to St. Johns. Fortunately, the engines were undamaged and perfectly operational after the salt was washed out, and the data collected during the mission was saved. According to the detailed NOAA Mishap Investigation Report posted on Chris Mooney's excellent blog
, "Post flight inspection of engines revealed significant white build up on intakes, first stage compressors, and CIP probes of all four engines. Subjectively, the #2 engine appeared to be the worst coated of all engines. Aircraft fuselage and windows were also heavily coated." Salt build-up on the engines was determined to be the cause of the incident. The unusually dry nature of the storm prevented the salt from being washed off, and was probably part of the reason the engines failed on this flight, and not on previous flights.
I asked Dr. Jim McFadden, project manager of the Ocean Winds project, what happened. He was on the flight, and responded: This event stumped everyone including the experts who spend a life-time studying sea salt and aerosols in the marine boundary layer. Six previous flights in similar conditions had resulted in nothing like this. But this one was different. It was flown over an ocean warmed by the Gulf Stream in a dry slot of cold Canadian air. Somehow that combination was the key to what could have been a disastrous flight. Fortunately, quick thinking and the flawless action of the crew brought about by excellent training got us home safely.
Last week in Washington D.C., the crew of Kermit was honored with the Department of Commerce's Gold Medal for successfully bringing home the aircraft. The crew members from NOAA's Aircraft Operations Center who were on the flight were:
LCDR Mark Nelson
LCDR Carl Newman
LCDR Peter Siegel
LCDR Joseph Bishop
QuikSCAT scientists Paul Chang and Rob Contreras were also present on the flight.
Separate Department of Commerce Gold and Silver Medals were also awarded last week for scientists involved in leading NOAA's operational use of NASA's QuikSCAT satellite to produce more accurate forecasts and warnings of marine and coastal weather:
Hugh Cobb III (NWS)
Roger Edson (NWS)
James Franklin (NHC)
Richard Knabb (NHC)
Kevin Schrab (NWS)
Joseph Sienkiewicz (NWS)
A Gold Medal is defined as distinguished performance characterized by extraordinary, notable or prestigious contributions that impact the mission of the Department and/or one operating unit and which reflect favorably on the Department. Congratulations to all the awardees, and thanks for all that you do!