• Guest, pentru o varianta fara reclame a forumului oferim conturi premium. Mai multe detalii aici.

Zsolt

King Nothing
Staff member
fly-ra 2017
Feb 12, 2012
6,631
2,126
113
39
EDDK
flightradar24 feed id
My fr24 statistics
flightaware feed
My flightaware feed
Flightdiary
My fr24 profile
#1
A very interesting story by J. HUDDLESTON

The weather at Saratoga Springs, N.Y. on the night of July 13, 2008 was 1,100 overcast, one-and-a-half miles visibility with moderate rain, and wind calm. Albany approach control vectored us for a GPS approach to Runway 5. We intercepted the inbound course toward the airport. On our descent, all altitudes and altimeters coincided with the information on the approach plate. Before reaching minimums, my co-captain called, “Runway in sight, twelve o’clock.” I responded, “Going visual.” Looking up, I saw the runway was dead on at 12 o’clock. Before going visual, all indications on the flight director were centered and exactly where I wanted them. My co-captain called, “Ref plus thirteen,” then immediately called, “Trees! Pull up, pull up.” I simultaneously went to max power and rotated to a 15-degree deck angle. The aircraft hit a pine tree and, we learned later, cut eight feet off its top. I still had the runway in sight, and after making a quick scan of the panel I replied, “We have good gear indication, and pressure is up; I plan on landing.” My co-captain replied, “I concur.”

Visual inspection after landing revealed substantial damage to the left wing of the Learjet 45. We learned later we had made the right decision to land from the approach and not attempt a go-around. The left flap was damaged severely enough that flap retraction on the go-around would likely have resulted in a split-flap condition that could have been catastrophic so close to the ground.

I lay awake most of the night, flying the approach over in my mind. I knew the aircraft was exactly where it should have been on the entire approach. I thought back on how many approaches I had made in my career, approaches such as NDBs that required the most skill of all approaches, and never having any problems. What went wrong? Finally, at three o’clock in the morning, I told myself that I had flown the approach as published, and it was the approach that had to be flawed.

A few days after I had given the FAA all the pertinent information it needed, I received a letter from the Albany FSDO stating that while I would not be subject to any enforcement action, the incident gave the agency reason to believe that re-examination of my airman competency was necessary under Title 49 United States Code Section 44709, which would require me to take a check ride with an FAA examiner. I answered the letter and followed up with a phone call to the FAA inspector who issued the letter, explaining that I had just completed a check ride three months earlier, that I had flown the GPS approach to Runway 5 at Saratoga Springs precisely as published, and that I was convinced the approach was flawed and should be checked. I also stated that by agreeing to take the check ride I would be admitting pilot error. The inspector said, “You can work that out with your local FSDO, and whatever they decide will be fine with me. I just have to clear my plate.”

Five days later, with temporary repairs completed and a ferry permit in hand, we were ready to fly the aircraft back to Nashville. The weather on departure was severe clear, with not a cloud in the sky. We called Albany Approach on departure and made a request to fly the GPS Runway 5 approach. They gave us vectors almost exactly like those we had received on the night of the incident. We intercepted the inbound course outside the IAF and continued the approach. I started the descent with reference to our glideslope indication, just as I had on the night of the incident. I wanted to maintain the three degrees as published on the approach plate. When we were approximately two miles from the runway it was clear we should no longer proceed: three degrees, if maintained, was going to put us into the tops of the trees. I broke off the approach and initiated a climb. Albany Approach cleared us on course and we departed.

After talking to some of my pilot friends back in Nashville–some of them instructors, one a certified engineer–I became convinced the approach was flawed. One of my friends, the engineer, took all the data from the approach plate and the data I had given him and came to this conclusion: a stabilized approach in a Learjet 45 at the weight we were the night of the incident, maintaining Vref+10 on descent for an approach at a three-degree glideslope with calm wind would make for a descent rate of 650 fpm and a descent gradient of 325 feet per nautical mile. Continuing the approach from the VDP to the runway at this rate for 1.2 miles would put the aircraft at 43 feet above the threshold. This was the profile we had flown on the night of the incident.

With this data in hand, I talked to the FAA Flight Standards Office in Oklahoma City, filed a user report on Saratoga Springs Airport and requested a Terps analysis and a flight check of the GPS Runway 5 approach. I called the FAA Hotline in Washington, reported the incident and told them I thought the approach was flawed and should be checked. I then took the data to the Nashville FSDO and met with two of their inspectors. After checking that data, one of the inspectors said, “Jim, if this data is correct, have you thought about a takeoff on Runway 23 having a problem?” (The Runway 23 departure was listed as a standard departure.) “No,” I replied. “I have enough to do with the incident on Runway 5, let alone Runway 23.”

Later, I had my engineering friend run the data for departing on Runway 23 in the Learjet 45. Using the FAA criteria for obstacle clearance, power failure on one engine after V1 and continuing the takeoff, accelerating to rotation speed, rotating, climbing at V2, crossing the end of the runway at 35 feet and maintaining a climb rate of 250 feet per nautical mile, the aircraft would hit the same tree, but at a much thicker part of its trunk, 84 feet lower than the height at which we had topped it. (The FAA will base a hazard decision on any departure requiring a climb gradient of more than 200 feet per nautical mile.) The data showed that a climb gradient of 350 feet per nautical mile would be required for the Learjet 45 to clear the tree 1,166 feet from the end of Runway 23, and even then it would clear the timber by a mere two feet. Under the same conditions, if the aircraft yawed by five degrees to the right it would hit much taller trees even at a climb gradient of 350 feet per nautical mile.

The FAA swung into action, and things began to happen. On August 6, Notams were issued prohibiting any and all approaches at Saratoga Springs Airport at night until further notice. On August 15, Notams were issued prohibiting the GPS approaches to Runways 5 and 23 and the VOR DME A approach at night until further notice. On September 4, a Notam was issued prohibiting the GPS approaches to Runways 5 and 23 at any time. On September 9 I received information from the FAA that it intended to prohibit GPS approaches to Runways 5 and 23 until the procedure was changed. This Notam remained in effect for eight months. The agency also marked 15 trees that had to be removed before it could reinstate authorization for the approach procedures to be flown. On September 10 an FAA inspector told me that the procedure for the GPS Runway 5 approach had been drawn using a 1990 survey that contained a 500-foot error. The 47-foot threshold crossing height should have been 500 feet farther down the runway, and several trees on that approach penetrated the obstacle clear line, some by as much as 80 feet. Three were more than 100 feet tall.

The insurance company carrying the policy for our aircraft conducted its own investigation, and its findings were startling. The factual summary stated: “Mr. Huddleston, the captain of the flight in question, was guaranteed by certification criteria a 20:1 obstacle clearance slope until the VDP (visual descent point) and a 34:1 obstacle clearance slope from the VDP to the runway threshold. A pilot flying a GPS approach with a VDP on the published approach plate is assured this margin of obstacle clearance. The subsequent tree survey showed the tree [that the aircraft struck] extended well into the 20:1 glideslope far in excess of the 34:1 required by this type of approach. The VDP feature of this type of approach assures the pilot that a 34:1 slope from the VDP to the runway threshold is free of obstructions.”

The insurance company’s consulting firm wrote a seven-page summary of its findings. The condensed version stated, “The pilots met all requisite FARs for a legal and safe flight and executed a proper GPS approach that contained a VDP terrain clearance component, and the airport authority did not maintain the requisite obstacle clearance required by FARs and New York’s DOT, causing penetration of trees into the protected zone around the airport property, which directly led to the incident.”

Documents provided by Saratoga County showed that every runway and every approach had trees penetrating the Obstacle Clear Line, and documents proved that these discrepancies were known about as far back as 1999. One document dated September 1999 stated, “Obstruction analysis study of Runway 5 identified ‘numerous penetrations’ to the approach surfaces, both on and off airport, and determined that ‘to maintain a clear 20:1 approach surface, the Runway 5 threshold would have to be displaced 946.5 feet’ [almost twice the 500 feet calculated initially].” Numerous documents and emails from the Saratoga County Department of Public Works and New York’s DOT were written between September 1999 and (more than two months after our incident) October 2008 addressing the issues, but no action was taken.

Two years earlier, in April 2006, one email stated: “FAA flyover inspection shutdown VASI on Runway 05. Flight Inspection Report states, ‘Obstacle clearance unsatisfactory due to trees near threshold.’” While no one took any action, these trees were growing at a rate of three to five feet per year. From September 1999, when obstacle issues were first identified, until the night of our incident on July 13, 2008, not a single tree on the approach to Runway 5 was topped or removed. An August 2008 email from NY DOT about the results of its inspection stated: “RWY 05-Trees +89’, 1035’ from RWY end, 9:1 slope.”

My main objective in writing this article is that it will prevent anyone from flying under the false impression that as long as you “fly the plate” you are protected. That might have been the case back in the good old days before we became so automated. Back then, all instrument approaches were flight checked. I have instructed and typed numerous pilots in Learjets, and for more years than I would like to admit I have preached to them, “Fly the plate and you won’t get hurt.” I quit preaching that on the night of July 13, 2008.

I wanted to write this article immediately after the FAA had verified the approach was flawed and prohibited the approaches because of tree penetrations, but ongoing litigation did not allow me to. I can only hope that similar incidents have not occurred in the interim.

Originally published by J. HUDDLESTON at ainonline.com