Safe Initial Climbs Can Mean Tradeoffs
A pilot’s first takeoff in a jet airplane is a true rite of passage, almost as eye opening as a first solo. Push those power levers forward, and a pilot’s body is soon pressed back against the seat. That feedback is tough to duplicate in a piston airplane. But jet power, speed, and flight safety—not to mention strict certification standards—demand a real understanding of the performance calculations that many new pilots today are trusting to an iPad app.
Ponder one departure myth, for instance—the one that claims jet pilots needn’t worry about engine failures at takeoff because of all the extra power waiting in those big turbines. Not necessarily. Matching true jet performance against these myths becomes much clearer through the scenario-based evaluations now demanded in the new airman certification standards.
The Engine-Out Performance Myth
Consider an engine failure just after rotation. Certainly a Hawker 800XP with one engine idled will climb better than a Cessna 310 with one throttle pulled back, won’t it? But like a twin Cessna, the climb performance of a jet drops off precipitously when one engine stops operating, depending upon how the change is measured.
On a standard day, even at maximum takeoff weight of 28,000 pounds, our Hawker 800XP’s power will rocket the aircraft from sea level to FL370 in about 20 minutes, at about 1,850 feet per minute. If an engine quits at that same weight, however, the airplane’s single-engine climb rate drops to approximately 470 feet per minute—a decrease of about 75 percent. How well the aircraft climbs after that, as in all aircraft, is also dependent upon the skill level of the person behind the controls. Looking back at the nearly negative single-engine climb rate of a light twin such as that Cessna 310, a 500-fpm climb rate might sound impressive. But there’s more to creating a safe departure in a jet.
Imagine our 800XP is departing Aspen, Colorado, an airport nestled between monumental peaks of the Rockies at a 7,838-foot elevation. Today’s outside air temperature (OAT) is 15 degrees Celsius. A quick check of the approach and departure plates highlight the first departure concern: the rocks. The minimum safe altitude (MSA) northwest of the field reaches just above 13,000 feet. Southeast of the airport, the safe altitude climbs to nearly 16,000 feet within just a few miles. Usable runway is 8,006 feet. So no big deal, right?
A close look at the Aspen Six departure is next to see if the Hawker’s takeoff performance can best any published restrictions. Plenty of runway, of course, and a check of the performance section of the aircraft flight manual (AFM) confirms that the Hawker can safely clear the runway—with one small glitch. The aircraft can’t do it at maximum takeoff weight. In a jet, the term usable runway length really needs a note that says “usable sometimes.” [Read more…] about Understanding Takeoff Calculations
Decades ago, when I learned to fly, it was well-known that a commercial co-pilot/first officer was allowed to occupy the right seat of a transport airplane only if they’d proven themselves subservient enough to understand that the guy in the left seat was perfectly capable of handling the airplane all by himself.
I remember riding our crew bus with a bunch of other pilots, and flight attendants in the spring of 1991 not long after our employer Midway Airlines had filed for Chapter 11 bankruptcy protection. The old red and white school bus ran the flight crews from the parking lot on Midway Airport’s north side parking lot along 55th Street to the terminal so we could connect with our aircraft. Since pilots have all the solutions to every problem on Earth (just ask one) a bunch of us were complaining about the current state of the airline and our future. Being a big mouth — yes, even then — I wondered why Dave Hinson, our CEO was still running the place. “If Hinson was in charge when we entered bankruptcy, why should we expect he’ll be able to get us out?” After a few nods, the back of the bus was quiet for a few minutes before we moved on to complaining about the crew meals.
On-demand flying always seems to happen in the middle of the night—or in this case early one morning. It was just past midnight when dispatch rang. My co-pilot, Jerry, and I were to fly the Citation empty to Atlanta, pick up four people, and deliver them to Orlando Executive Airport. “OK,” was about all I could think to say at first since dispatch had just woken me out of two whole hours of deep sleep. “Can you tell me about the trip again?” I asked. I climbed out of bed and got a quick shave and shower before climbing first into my uniform and then my car headed to the hangar.
(Click the player above for audio)