Cessna 172M similar to accident aircraft. Photo by Durksteel (Public Domain Image)

Last week, the National Transportation and Safety Board (NTSB) released their preliminary report on the Rimrock, Washington plane crash that killed two and in which only a five year-old girl survived.  The accident happened on June 28, 2009 at 3:10 PM PDT and involved a Cessna 172M Skyhawk (registration N4396R).  Killed in the accident were Justin Reed and his son Parrin Reed (13).  Julie Reed survived the accident.  You can see the original post about the accident HERE.

While I pointed out on the original post that I did not know if the airplane was landing at Tieton State Airport (4S6) or what its flight path was, the NTSB preliminary report (WPR09FA316) clears this up.  The Cessna departed out of Yakima Air Terminal/McAllister Field (YKM) in Yakima, WA at 2:41 PM and was headed to 4S6 where the wife/mother of the accident victims was waiting in a car.  Witnesses at the airport say the aircraft approached from the west side of Tieton and appeared to be trying to land in Runway 02.  The airplane was still flying three-quarter of the way above the 2,509 feet runway when the pilot added power and began to climb out.  Witnesses say the airplane climbed out at a high angle of pitch and they could easily see the top of the wing surface.  The plane then struck a tree with its left wing and crashed to the ground.  The wife of the pilot did say she considered the day very breezy and thought it would be difficult to land in the strip.  It was unclear from the report or from weather observations if the airplane encountered a tailwind, which would have made landing more difficult and the climb (as a function of distance traveled) less efficient.

4S6 is a particularly difficult airport to land in.  The preferred way (if not the only way) to land is to come in from Rimrock Lake to the west as there are 4,500-6,515 feet peaks in just about every other direction (see Google Maps below).  I posted THIS LINK on the previous post that included pictures of the airport (NOTE: this is an external link that will take you to another website).

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Assuming there aren’t any unexpected factors, like a father letting a child have a go at landing, this accident may have occurred as a result of an improperly executed go-around that did not take into consideration a few factors at 4S6.  For one, going three quarters of the way down a 2,500 feet runway that has high terrain immediately following it is definitely dangerous.  I think Tieton State is one of those airports in which a pilot needs to judge his/her approach a little bit more strictly than they would at another airport such as YKM.  If the approach doesn’t look good, the pilot may want to go around at that point or at least make his/her decision on the first few hundred feet of runway.  A pilot cannot have the same criteria for going around at every airport they visit.

Another issue I wanted to discuss here (and a few of you mentioned this on e-mails relating to this accident) is density altitude.  For those of you that are not familiar with density altitude, the term describes a theoretical altitude calculated by taking the actual altitude an aircraft is at and adjusting it for the effects of changes in temperature and atmospheric pressure.  Since temperature and atmospheric pressure change all the time and these changes have an impact on the density of the air, pilots need to take these changes into account because it affects the performance of the aircraft.  Going back to the accident, the NTSB report does list the temperature as 28°C (82.4°F), dew point as 3°C (37.4°F), and atmospheric pressure as 30.02” Hg.  These factors result in a density altitude at 4S6 of 5,082 feet, which is high enough that it must be considered in flight decisions.  While I have not personally flown a Cessna 172M model, I can use the Cessna 172P model’s performance to give an idea of how density altitude changes affect airplanes.  On that model, the change in density altitude results in a loss of nearly 300 feet per minute in climb performance and it will take nearly three times as much distance over the ground to reach an altitude that cleared some of the obstacles around the airport.  So, the accident plane was faced with greatly decreased climb performance that only made the late go-around more dangerous.  Of course, if there was a tailwind present, this would have only been worse.  (As a frame of reference, had the pilot been taking off that day from the airport eastward—even if this is never done—the distance to clear a 50 foot obstacle after takeoff would have been approximately 5,150 feet from the takeoff start point.  In other words, the plane would have probably hit a tree).  I should point out that some of the people at the airport ran towards the airplane after it began its go-around.  So it may have been apparent to them that the go-around was started too late.

Of course, all these assumptions are based on the NTSB preliminary report’s information.  As I always say, unless we were in the cockpit that day, we don’t really know all the factors in the accident.  However, this does appear to be an improperly executed go-around that did not take into consideration the density altitude at 4S6 or the obstacles on the other side of the runway.

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You may be interested in:

• Original post on the accident.
• NTSB preliminary information on Cottonwood, AZ RV-6A crash.
• NTSB preliminary report on Sheldon, Iowa plane crash.
  

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