Obstacle departure procedures

Illustration by Kevin Hand

This illustration depicts the Runway 19 obstacle departure procedure at the time of the accident cited. Since then it has been revised, removing the NDB hold. (Not for navigational purposes.)

You’re departing Morrisville, Vermont (MVL), in your new light jet on a low-IFR day. As Morrisville is nontowered, a call on the ground communication outlet (GCO) to Burlington Clearance Delivery yields clearance to the CAM VOR, then as filed. Because of a short clearance void time, you elect to depart Runway 19—closest to the ramp and sloped downhill, but with a slight tailwind.

When creating your FMS flight plan, what should be the first fix? Many pilots would answer “CAM,” and sadly a piston pilot fatally crashed into a peak just south of Morrisville flying a similar path. To correctly determine the first fix in the flight plan, consultation with the obstacle departure procedure (ODP) is required. At the time of the accident, the Runway 19 ODP directed the pilot to make a turn northbound to the JRV NDB until reaching a specified altitude—the opposite direction from the first en route fix of CAM.

ODPs are one of the best kept “non-secrets” in flying. They often are difficult to find and almost never assigned by ATC, so it’s understandable many pilots have a hazy understanding of ODPs. The FAA creates an ODP if obstacles require that a climb of more than 200 feet per nm be maintained for acceptable terrain separation. In conjunction with a prescribed lateral path, the ODP often will require that the aircraft be able to maintain a specified climb gradient steeper than the standard 200 feet nm.

The Aeronautical Information Manual defines pilot responsibility regarding ODPs. Pilots are directed to consider the terrain in the vicinity of the airport, and if an ODP is available, determine if it should be flown or if visual obstacle avoidance is possible. Further, the pilots of multiengine aircraft are directed to consider the effect of degraded climb performance and actions to take in the event of an engine loss.

ODPs may be flown without ATC clearance, unless an alternate departure procedure or radar vectors specifically have been assigned. In all cases obstacle clearance is not provided by ATC until the controller begins to provide navigational guidance in the form of radar vectors. ODPs are usually depicted in text, not graphic, format and are located in the front of the NACO chart book and on the bottom of the airport information page in Jeppesen’s.

It is a common, but mistaken, belief that jets must be able to maintain the specified climb gradient of an ODP or standard instrument departure on one engine. The AIM is explicit in stating that both ODPs and SIDs assume normal aircraft performance with all engines operating.
At many high mountain airports, maintaining the steep climb gradient of an
ODP on one engine would simply be impossible. Pilots are directed instead to develop contingency procedures to cover the case of an engine failure during or after takeoff, which may differ in track from the ODP. AOPA

Neil Singer is a Master CFI with more than 7,200 hours in 15 years of flying.