The point of no return
is the point beyond which
someone, or some group of people, must continue on their current
course of action, either because turning back is physically
impossible, or because to do so would be prohibitively expensive or
dangerous. It is also used when the distance or effort required to
get back would be greater than the remainder of the journey or task
as yet undertaken.
A particular irreversible action (e.g.
off an explosion or signing a contract) can be a point of no
return, but the point of no return can also be a calculated point
during a continuous action (such as in aviation).
Origins and spread of the expression
The term PNR
—"point of no return," more often referred to
by pilots as the "Radius of Action formula"—originated, according
to the Oxford English
, as a technical term in air navigation
to refer to the point on a
flight at which, due to fuel consumption, a plane is no longer
capable of returning to its airfield of original takeoff. After
passing the point of no return, the plane has no option but to
continue to some other destination. In this sense, the phrase
implies an irrevocable commitment.
For nonstop flights between two definite locations, the PNR is
the halfway (more exactly, the "equitime")
point, since aircraft usually carry more fuel than is necessary to
reach the destination. For example, on a 2000-mile flight, should
the tanks have enough fuel for a 3000-mile flight, the halfway
point would be at 1000 miles, but the PNR would be at more than
Neither does the PNR correspond to the halfway point of fuel usage.
In the latter half of a flight, the aircraft's mass will have
decreased due to fuel expenditure and is thus more fuel-efficient.
So an aircraft might expend 60% of its total fuel load before
reaching the PNR. The PNR can be further extended in this manner by
dropping unnecessary fuel tanks or ordnance.
Another aviation use is the point during the takeoff roll when
there is no longer enough runway ahead of the airplane to stop
safely; at this point, the aircraft is committed to taking off.
(See also V1 speed
.) In mountain
aviation, the phrase is sometimes used in a completely different
way to refer to the point at which the grade of the terrain
"outclimbs" the aircraft—that is, the point at which a crash is
inevitable, being a parallel in common usage. The phrase can also
be used in this sense to denote inevitable disaster.
The first major metaphorical use of the term in popular culture was
John P. Marquand's novel "Point of No Return" (partially serialized
in 1947, published in book form in 1949). It inspired a 1951
Broadway play of the same name by Paul Osborn. The novel and play
concerned a pivotal moment in the life of an American banker, but
they also explicitly referenced how the original expression was
used in World War II aviation.
Since then, "point of no return" has become an everyday expression,
with its aviation origins probably unknown to most speakers. It has
served as a title for numerous literary and entertainment
There are a number of phrases with similar or related
- Crossing the Rubicon is a metaphor for deliberately proceeding past a point
of no return. The phrase originates with Julius Caesar's invasion of Ancient Rome when, on January 10, 49 BC, he led
his army across the Rubicon River in
violation of law, hence making conflict inevitable. Therefore the term
"the Rubicon" is used as a synonym to the "point of no
- Alea iacta
est ("The die is cast"),
which is reportedly what Caesar said during the aforementioned
crossing of the Rubicon.
- The equivalent expressions
- Burn one's bridges. The expression is derived
from the idea of burning down a bridge after crossing it during a
military campaign, leaving no option but to win, and motivating
those who otherwise might want to retreat. This expression can also
be used figuratively, as in, "On my last day at my old job, I told
my boss what I really think about the company. I guess I burned my
- Burn one's boats, a variation of burning one's
bridges. The Muslim commander Tariq ibn Ziyad, upon setting foot on the
Peninsula in 711,
ordered his ships to be burnt, so that his men had no choice but to
thrust forward and conquer the peninsula.
- "Break the woks and
sink the boats ", an ancient Chinese saying referring
to Xiang Yu's order at the Battle of Julu; by fording a river and
destroying all means of re-crossing it, he committed his army to a
struggle to the end with the Qin and eventually
accompli ("accomplished deed", from the verb
"faire", to do), a term of French origin denoting an irreversible