Was curious as to why the radio talk over a Space X rocket launch uses the following words uttered by the technicians at various times…
Propulsion system still nominal
Front whatever still nominal
This and that …still nominal
Why ‘nominal’. Doesnt it mean exist in name only?
It can also mean “satisfactory” or “within tolerances” or “according to plan.” In space jargon it just means “the thingy is doing what we expected.”
Nominal can also be translated to mean “as nominated”.
A lot of people expect the word “normal” to be used. Propulsion still normal etc etc. Normal behaviour may however be the rocket exploding and destroying everything in sight.
Nominal can also mean very small in relation to the norm. “How about they charge cyclists a nominal road tax fee which could go towards pothole repairs?”
I suspect that the full phrase might be “Propulsion system still with only nominal variation” or something similar. They could use “normal” - but maybe that has some different meaning in that context.
Engineering criteria have a precise ‘nominal’ vaue, plus or minus tolerances.
However, in the reporting context presented here, ‘nominal’ has become accepted shorthand for ‘within acceptable tolerance of the nominal value’.
Much discussion here:
Many thanks. Answers my question. Wish we had a like button.
I recall the phrase “Still nominal on consumables.” being used several times during the Apollo 11 landing.
“Notional” means to exist only in concept, e.g. a notional design or a notional bill. Nominal means at the expected value or within an anticipated range.
As for why the controllers call out nominal conditions rather than reporting by exception, they are following a script which ensures that they are communicating with the other controllers and launch director and are tracking all of the associated parameters. This is frankly a somewhat arcane practice as there is nothing that can be done to fix problems in flight, and largely serves to inform the Range Safety Officer as to whether to anticipate a potential flight destruct scenario, though the ultimate decision on flight destruct is almost always whether the vehicle is approaching the hazard lines posing a potential ground/shipping hazard if it were to go off course or break up outside those lines.
Stranger