Not sure if we're on the right track at all here...but here goes.
On some types of aircraft (Modern Boeings for sure) there are TWO ignition selectors (two igniters per engine).
Depending on the 'selected' position, and what systems use it, an 'inop' igniter (subtle or obvious) 'selected' will obviously be of no use.
We have procedures, albeit not the Classic 747, to select 'BOTH' AFTER engines started. We select one igniter (left) for east-bound flights and the other (two, right) for west-bound flights during pre-flight for engine start.
Should the engine fail to start due igniter failure, all is obvious.
Should the igniter fail after engine start, and if it is NOT in BOTH position, then crew WILL be unaware of the failure until the next time the engine is started with that igniter selected (unless there is a failure detection system - no EICAS mesage on our type of aircraft).
Anti-ice uses the 'selected' igniter on MOST aircraft.
If you select BOTH after engine start, the likelihood of both having failed without pilot knowledge, is remote (has happened), however, the remaining igniter WILL be available for Anti-ice usaeage.
Now, on the classic (of which I know nothing! - sadly born in a different generation), MAYBE the Anti-ice check served the same outcome.
A look into the systems of igniter (selected) VS. anti-ice might help understand the 'type' situation.
Hope this is helpful.
Here's to ice-free engines!
