Answer by Tom Farrier, Retired US Air Force command pilot; Current aviation safety contractor for the government, on Quora:
Landing is generally considered quite a bit more hazardous (and requires a bit more exacting handling), but both takeoffs and landings can have their challenges. Still, aircraft like to fly; sometimes it can be a little tricky to encourage them to stop doing so at the end of a flight, especially in the presence of unpredictable winds or slippery runways.
This is a graphic from my favorite go-to reference on commercial aircraft accidents, updated annually by Boeing but including all airliner accidents:
The shaded area under the aircraft silhouette shows the amount of time an aircraft spends in each “phase of flight.” At the top, there are two numbers worth looking at carefully. Final approach and landing is when 48% — essentially half — of all fatal accidents that have occurred from 1959 through 2016. By contrast, taking off and starting to climb is only about a quarter as hazardous (13%). These ratios used to be somewhat different; takeoffs used to see their share of accidents a lot more frequently than today.
The biggest challenge with taking off in the early days of jet airliners was the rate at which they could accelerate during their takeoff roll. Often, a lot of time was required between when the aircraft passed the speed at which the pilots were committed to taking off (V1) and when the jet actually could get into the air with a positive rate of climb. When an emergency would suddenly present itself in that window of vulnerability, sometimes there were no good options, and sometimes the pilots picked the wrong one.
One of the biggest ways pilots (and flight engineers in aircraft that use them) have to earn their paychecks is when something bad happens during a takeoff roll and they have to decide whether to continue the takeoff and deal with the problem in the air, or if the situation is critical enough that it’d be preferable to wrestle the fuel-laden beast on the ground and risk going off the end of the runway.
To try to address the need for added clarity in such situations, some of these early accidents led to recognition of the need for establishing a second speed benchmark (V2), which is the point at which the aircraft is going fast enough to make a successful takeoff with one engine out. Bear in mind that a lot of the biggest early jets had four engines, none of which was nearly as powerful as the current generation (some actually used water injection systems to boost their thrust during takeoff), and which suffered failures a lot more often.
“Rejected takeoffs” are pretty rare occurrences these days, and airport design has gotten better at minimizing the consequences of an aircraft running off the end of a runway if circumstances conspire to make things exciting for its inhabitants. For example, “engineered material arresting systems” are basically long slabs of pavement designed to collapse under the weight of an aircraft, grabbing hold of it and bringing it to a fairly enthusiastic stop.
This may not sound desirable, but some of the places EMAS has been installed (e.g. Boston’s Logan, New York’s LaGuardia) have seen more than their share of aircraft in trouble winding up in bodies of water during what are euphemistically (but accurately) referred to as “runway excursions.” Such departures can happen during either takeoff or landing emergencies, and it’s nice to know that the chances of surviving both have been improved significantly with one ingenious invention.