NTSB Preliminary Report on Saratoga Crash at Pine Mountain Lake in Groveland, California

Posted on February 25, 2010 by Mike Danko

The NTSB released its preliminary report on the Pine Mountain Lake crash.  As usual, the preliminary report contains no conclusions concerning the cause of the crash. For that, we'll have to wait up to 4 years.  The preliminary report does, however, hint that the NTSB's investigation will focus on whether the pilot pressed on into weather beyond what the regulations allowed.

The full text of the report is here.  Some excerpts:

Instrument night meteorological conditions prevailed at the accident site, and no flight plan had been filed.

Instrument weather conditions are those that require a pilot to fly by reference to his instruments rather than by looking out the window. To fly in instrument conditions, a pilot must be instrument-rated, his plane must be properly equipped, and he must have a clearance from air traffic control.  He is not necessarily required to file a flight plan.  For example, instead of filing a flight plan, the

pilot may have departed San Carlos in good weather and then obtained a "pop-up" clearance from air traffic control before entering instrument conditions at Pine Mountain Lake.  Nothing unusual or unsafe about that. 

A pilot, who stated that he flies to the airport most weekends, reported attempting to Cessna 510land a Cessna 510 while on an instrument flight plan, about 1 hour prior to the accident. He reported that throughout the instrument approach he was unable to identify the runway environment. He performed a missed approach, and diverted to Modesto where he landed uneventfully. He stated that he has flown into the airport utilizing the instrument approach regularly over the last few years, and this was the first time he had to divert to an alternate airport.

As discussed in this post, crash, a pilot on an instrument approach to runway 27 must "go missed" if he descends in the clouds to the minimum allowable altitude  -- in this case 770 feet above the ground --  and still can't see the runway.  Instead of going missed as required, some pilots will descend "just a little further" believing that, in just a few more seconds, they will break out of the clouds and the runway will appear before them.  Descending below the minimum altitude set forth in the instrument approach procedure is a violation of FAA regulations and a leading cause of instrument approach-related accidents. The NTSB seems to suggest that the pilot of the accident aircraft, N4175A, must have ventured below minimums to get beneath the clouds because the Cessna jet had to go missed.  However, the fact that the Cessna was forced to execute a missed approach at the airport one hour before the accident means little. Weather can change in an hour. 

The remaining two propeller blades were attached at the hub. All of the blades exhibited leading edge gouges, and varying degrees of tip twist. 

Gouges and blade twist is an indication that, the time of impact, the engine was developing power. Engine trouble can likely be ruled out.

A third witness, located 1/2 mile northeast of the approach end of runway 27, heard a low flying airplane, which he presumed was flying directly over his house, with engines running "full bore."

What was the pilot doing 1/2 mile northeast from the runway? (See image below.) As discussed in this post, the pilot should have been lined up for a straight-in approach.  And during the approach procedure, the pilot should have been throttled back for descent.  A pilot typically applies full throttle only when going missed.

Related Post: Piper Saratoga Crash at Pine Mountain Lake   

Location of NTSB Full Throttle Witness

 
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Piper Saratoga Crash at Pine Mountain Lake Airport in Groveland, California

Posted on February 22, 2010 by Mike Danko

The runway at Pine Mountain Lake is oriented east-west, and is surrounded by rugged terrain.  In poor weather, pilots are permitted to execute instrument approaches to the airport.  The approach procedures guide pilots as they descend through the clouds to the runway.  The procedures, flown properly, will place the pilot in a position to land straight ahead without having to maneuver.  When the pilot pops out of the clouds after flying the instrument approach to Pine Mountain Lake, his view out of the windshield should be something like this:  

 Final Approach Runway 27 Pine Mountain Lake - Photo by austinpilot  

The procedure the pilot must follow when approaching from the east is set forth below.  A pilot may descend in the clouds no lower than 770 feet above the runway.  To descend further, the pilot must

be clear of the clouds and have the runway in sight.  If he cannot see the runway, he must "go missed."  That means he must abort the landing, and climb straight ahead by reference to his instruments until reaching a safe altitude.

 Pine Mountain Lake Instrument Approach Procedure

 

Once the pilot has reached a safe altitude and has established radio contact with air traffic control, the pilot may attempt the approach procedure again.  He may obtain a clearance to fly a different approach procedure from the opposite direction, or he may opt to fly to a different airport where the weather is better.  

Investigators report that the accident aircraft, N4175A, "went missed" on his first approach to the airport, and that the accident occurred near the completion of its second approach.  On the second approach, the aircraft had successfully descended beneath the clouds.  We know that because a witness on the ground saw the aircraft maneuvering.  The witness saw the aircraft suddenly burst into fire, and then saw the aircraft crash. Investigators say that the aircraft exploded in flight because it hit a tree while maneuvering, and the tree ruptured a fuel tank. N4175A Point of Rest

The question is not why the aircraft hit a tree.  Rather, the question is why the aircraft was maneuvering at all.  The approach should have lined up the pilot for landing straight ahead.  No turns should have been necessary.    

It is true that pilots are permitted, once the runway appears before them, to circle around to land in the other direction if the surface winds require it.  But this accident occurred after dark. "Circling to land" in poor weather at night is a challenging undertaking.  There is a risk of losing sight of the runway, becoming disoriented in the dark, inadvertently re-entering clouds, or hitting obstacles that are hard to see.  That's why the "night circling approach to minimums" is considered the most dangerous of all instrument approaches.  Most pilots will not attempt a circling approach at night unless there is no other option.  Here, there was an option.  If the winds required landing in the other direction, the pilot could simply have flown the other available approach procedure which brings the aircraft straight in to the runway from the west. 

The NTSB will now take over the accident investigation.  It will be difficult.  Air traffic control tapes are often useful in reconstructing accidents such as this one. But there is no control tower at Pine Mountain Lake, and so the pilot would not have been communicating with any air traffic control facility in the final stages of the flight. 

The NTSB will also be interested in the weather conditions that the pilot encountered.  In particular, it will try to determine the altitude of the cloud bases, the direction and strength of the surface winds, and how far the visibility was.  But there isn't any weather recording equipment at Pine Mountain Lake, either.  The closest equipment is 15 miles away, at Columbia Airport.    

Photograph of the accident aircraft, Piper Saratoga N4175A, departing Oshkosh last summer. 

Update: NTSB Releases Prelimary Report
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