Story ID: 046
Weighing High-altitude Capabilities in Purchase Decisions
By: Kevin O'Leary
Caption: A review of high-altitude-certifed aircraft finds that most do not use the capability, but it can be helpful in certain circumstances.
Word Count: 826
Since the Wright Brothers invented the aircraft, original equipment manufacturers (OEMs) have tried to build aircraft that fly higher, faster, and further than all other competitors.
In warfare, an aircraft with a higher max altitude could be a huge advantage in that it could attack from above or climb to escape. In the same fashion, as a bird of prey taking out its target from above, the German Messerschmitt Me262 jet could climb faster and higher than Allied piston-powered fighters.
This altitude advantage allowed the Me262 to attack Allied bombers from above. If the Germans had developed the Me262 a couple of years earlier, this altitude and performance advantage could have changed or at least delayed the outcome of WWII.
However, does a higher maximum certified altitude (HM) make one business jet a better purchase decision than another? Those that agree will boast about the ability their aircraft has “to get up high” and sip fuel, fly over thunderstorms, avoid other traffic, and receive more direct routing.
These may all be real-world advantages of using these higher altitudes but how often are these HM aircraft able to benefit from these advantages? Are these meaningful advantages of HM business jets or just hype that lacks substance?
To gain insight into this, my firm, Jet Advisors, conducted a study of 29.8 million IFR flights either arriving, departing, or flying point-to-point in the U.S. Ninety-one different jet types were included.
Studying High Altitude Flying
Our study initially looks at all business jet flights that achieved an altitude greater than 35,000 feet (FL350). Since most business jets are not certified to fly above 45,000 feet (FL450), we then focused on altitudes achieved by HM aircraft on all flights, and subsequently, on longer flights where it makes more sense operationally to climb to higher altitudes.
Comparing altitudes above 35,000 feet, the study found that most business jets fly at 41,000 feet or FL410. A large number of flights also use FL430 and FL450. There is a dramatic drop-off after FL450. This is likely because many aircraft are not certified to fly higher than those altitudes. But despite being the most popular altitude, FL410 is only used by 8 percent of all business jet flights.
Since it is logical that shorter flights wouldn’t benefit from higher altitudes, the study also analyzed longer flights, defined as those greater than 1,000 nm. About 3.9 million business jet flights were considered long. Nearly 16 percent of long flights were at FL410 and 44 percent were flown between FL410 and FL450. 
The study then considers high-altitude flying. Only 23 of the 91 types in the study are certified to fly above FL450, and we examined 8.3 million flights flown by these HM aircraft. There is a distinct pattern showing that after FL470, flights drop off dramatically. It also shows that FL470 only represents 1.4 percent of all flights for HM-capable bizjets. Of some 1.6 million long flights involving HM aircraft above FL450, the largest percentage was at FL470.Percentage of Flights Above FL350 (All Bizjets). Chart: Jet AdvisorsPercentage of Flights Above FL450 (All Bizjets on Long Flights). Chart: Jet AdvisorsPercentage of Flights Above FL450 (HM Bizjets). Chart: Jet AdvisorsPercentage of Flights Above FL350 (All Bizjets on Long Flights). Chart: Jet AdvisorsPercentage of Flights Above FL450 (HM Bizjets by OEM). Chart: Jet Advisors
Our study also showed which aircraft types are making the most use of the airspace above FL450. Gulfstream is clearly the leader but it's worth noting that the flights on Gulfstream products capable of flying over FL450 still only use airspace above FL450 on only 8.9 percent of their total U.S. flights (including international departures and arrivals). None of the HM aircraft types in the study flew more than 2 percent of all their flights over FL470 and most flew nearly zero flights at those altitudes.    
What are the answers to the questions of whether an HM has a material operational advantage over one that does not and whether that should that be a criterion for buying a certain aircraft type for primarily domestic use? The data suggest that ultra-long-range aircraft such as Gulfstreams need this capability on international/North Atlantic routes.  
But for aircraft used for domestic trips in the U.S., HM is not a material criterion for a purchase decision and has little operational advantage over other aircraft.  
As always in aviation, there are exceptions where high-altitude capability can make a certain critical trip non-stop, and then max certified altitude needs to be considered.    
Kevin O’Leary, Ph.D., is the CEO and founder of Jet Advisors, an aircraft acquisition, brokerage, consulting, fleet planning, and insurance firm.
The opinions expressed in this column are those of the author and not necessarily endorsed by AIN Media Group.