Eagle, CO KEGE
In the February T &T, we looked at Obstacle Departure Procedures (ODPs) and Standard Instrument Procedures (SIDs). Today, let’s see what happens if an engine fails during takeoff or shortly after departure. It is interesting to note that pilots flying under FAR Part 121 and 135 while departing an airport under IFR are required to use an engine-inoperative takeoff obstacle clearance or avoidance procedure. The Instrument Procedure Handbook states that the One-Engine Inoperative (OEI) assessment planning process “is separate and independent of the IFR departure procedure associated with the all-engines-operating climb gradient requirements.” Another interesting note is that the FAA does not require but rather “encourages” Part 91 operators to follow the same OEI planning process. Although most of my flying has been Part 121 and 135, all the Part 91 operations I flew followed the recommendation and conducted OEI planning. The consequence of not doing this could be grave.
The industry standard has been to purchase tailored Engine-Out Procedures (EOPs) from a business such as Aircraft Performance Group (APG) or ForeFlight. I have used APG for many airplanes, including CRJs, Boeings and Challenger Jets. I currently use ForeFlight for the Challenger Jets I fly. The one-engine inoperative procedure is a designed flight path considering aircraft performance, weight, and obstacle clearance along the OEI flight path track. But unlike ODPs and SIDs that show required climb gradients, the OEI procedures display their information in max takeoff weight. The higher the required climb gradient, the more the maximum takeoff weight is reduced. Part of our standard protocol is to brief the departure procedure for a normal two-engine departure and the one-engine inoperative procedure in case of an engine failure.
The Engine Out Procedure may be:
- Fly runway heading.
- Tailored route.
- Identified as a SID (may or may not be your
assigned SID).
Most EOPs dictate flying runway heading or straight out; however, the procedure will provide a route to follow if there are obstacles or terrain in the path. ODPs and SIDs begin their obstacle clearance assessment at 35 feet above the departure end of the runway (DER). Unlike ODPs and SIDs, the OEI obstacle fight path starts its obstacle assessment when the aircraft reaches 35 feet above the runway, using a portion of the runway for obstacle clearance. Another difference is that the OEI must account for “low close-in obstacles” that are not required for climb gradients in ODPs and SIDs.
For a contract trip to Toluca, Mexico, with a Fortune 500 company, the director of aviation asked if I would review the OEI procedures and run some numbers as this was their first time flying to this destination with an airport altitude of 8,466 feet. I did that and test-flew the procedures with an engine failure in a flight simulator at the charted maximum takeoff weights and temperatures. Not everyone has access to a fourteen-million-dollar simulator to test-fly their upcoming trips. Still, I was lucky to be able to back up the information provided by APG.
The APG data and the simulator practice with engine failures at V1 confirmed that we could take off with up to 14,000 pounds of fuel, up to 21 degrees F. It was interesting to observe the rising terrain while I flew up the valley, per the engine out procedure, with a negligible but adequate single-engine climb rate. When it did come time for the actual departure from Toluca MMTO Airport, the temperature was a few degrees cooler, and we only needed 13,000 pounds of fuel. Both engines kept running fortuitously, so the climb out was much better than I encountered during my simulated test flights.
The goal is to find an OEI departure procedure that mirrors the normal ODP or SID you are flying. This pre-planning eliminates a lot of busy work during an emergency engine failure. Most operators, including training companies such as FlightSafety and CAE, recommend loading the FMS, briefing your normal SID/departure, and loading the one-engine inoperative departure into the secondary flight plan. If you lose an engine on takeoff, all you or your co-pilot, if you have one, must do is activate the secondary flight plan. Some pilots “split the boxes” or un-synchronize the FMS boxes to separate the all-engine versus the OEI procedure. The problem with that technique is that you must re-sync the FMS CDUs after every takeoff without an engine failure, significantly increasing the chance of an error due to being heads down during a busy time.
The more complex the OEI procedure becomes, it’s usually rewarded by an increased maximum takeoff weight (see analyses chart above). The more complex track follows the best route to avoid obstacles and terrain. You should look at and plan for these even in VFR conditions, as this will provide you with the safest route in an emergency situation. Last week, I was flying out of Eagle, CO and cleared for the BEVVR 1 RNAV Departure. ForeFlight offered two engine-out departure procedures for runway 25. The first is “Straight out.” Interesting as that sounds, it is not even an all-engine departure option due to the mountain off the departure end of the runway. The next EOP mirrored the BEVVR 1 SID, except for the climb in the holding pattern.
Maintain runway heading until DER.
Then turn left direct COPER.
Then on track 264 to HNDES.
Then on track 308 to BEVVR.
Then on track 003 to APRES.
Climb in holding pattern at APRES, right turns, 5 NM legs, 003 inbound course.
This routing curves around the mountain, off the departure end of the runway, just as the SID does. The difference between the “Straight out” fly over the mountain and the fly around the mountain is the Maximum Allowable Takeoff Weight (MTOW). The “Straight out” allows for an MTOW of 35,087 lbs. The circuitous routing allows for an MTOW of 39,898 lbs. That’s an extra 4,811 lbs. of fuel. This additional fuel allowed me to fly non-stop to the East Coast rather than stopping at Denver to top off. (For reference, the Structural MTOW for the Challenger is 48,200 lbs.) Many other airports, such as Aspen, Rifle, Jackson Hole, and Boyne Mountain KBFA offer similar OEI departure procedures.
In the simulator training world, most engine-out departures commence with engine failure at V1. As a simulator instructor, I was privileged to train divergent procedures to pilots for a large Part 135 company. Advisory Circular 120-91A states: “Consideration should be given to the possibility of an engine failure occurring after passing the point at which the OEI track diverges from the normal departure track. Judicious selection of this point would simplify the procedure and minimize the difficulty of this analysis. This is generally achieved by keeping the two tracks identical for as far as is practical”. For our simulator training session, we would assign the clients to fly a SID with a departure procedure to the right or northeast and provide them with an OEI procedure with a turn to the left or northwest. Instead of initiating an engine failure at V1 speed while on the runway, we would allow the crew to fly the SID, fail an engine a few hundred feet in flight, and then watch what they would do. Most of the pilots stayed on the assigned SID, and this worked most of the time. Considerations need to be given to how much altitude they gained, how steep the climb gradient on the SID is, and any potential obstacles between the airplane’s present position and the OEI track. This is another reason for keeping the tracks as near as practical.
While there is no official requirement to analyze OEI missed approaches or rejected landings, the FAA states that it may be prudent to do so under some conditions.
AC 120-91A states:
“However, further analysis may be required in the following circumstances:
A published missed approach has a climb gradient requirement.
The DP for the runway has a published minimum climb gradient.
A special OEI takeoff procedure is required, or
There are runways that are used for landing but not for takeoff.”
OEI departure procedures are much easier to plan and set up today, with most of this information available at our fingertips via our iPads than yesteryear when I had to search through droves of paperwork prepared by dispatch. The best practice is to have a plan just in case you have an engine failure at the worst possible time. While attending your next recurrent training session, you may request to practice any of these OEI procedures. I did just that last month when I requested and practiced an engine failure at V1 speed and flew the OEI engine out procedure at Aspen, CO (KASE). I have a scheduled trip to Aspen in a few days. This practice will help me feel more comfortable with my departure and even put a smile on my face when both engines keep working, compared to my sim world.
