A320 Why do lot of pilots start chrono while starting engines?
 

I have seen a lot of pilots start chrono while starting the engine in A320.

It is not mentioned in the SOP anywhere and I couldn't find its utility.

Any good reason to do that?

There will be a limit for starter usage.

Are you asking about the first flight of the day (or if 2 hours passed since the previous flight), or in general? Just curious.

On the IAE engines we're looking for ignition on after 30 seconds, these engines have a dry crank first and take longer to start than the CFM ones.

Starting the chromo while starting the engines is a TECHNIQUE, not an SOP. The rational is that if you have a start abort and subsequently have to complete a dry crank and or manual start, it is the only way of monitoring the amount of time you have had the Start Valve Open with respect to the Engine Starter Limitations.
Other people can argue the validity of this technique.

After start, after a shut down period greater than 2hrs, to avoid thermal shock, the pilot should operate the engine at or near idle for at least 5min before advancing the thrust levers to high power (above 40% N1). That is SOP.

After start it is for that reason.

On the CFM, you have 15 sec maximum after you got the fuel flow to get an N1 and EGT increase.
Most people start the timer once the ignition starts, which makes no sense.
It is not SOP as everything is controlled by the FADEC and in case of a manual engine start the sequence is not the same (first you reach maxi motoring speed then you put the eng master on).

The starter time limit is observed by FADEC. For manual start, there will be an ECAM warning.

We tap the chrono to comply with a company 3 minute warm up requirement. We also do the same on landing for single engine taxi.

It’s probably a hangover from the old days of Instrument Rating Renewals where you got bonus points for starting your stopwatch as many times as possible during the detail... ;)

Not in the SOP's but it is mainly to respect the 2' idle thrust before taxiing. But it is also helpful to monitor the starting sequence of the engine. Beside that in case of a manual start it is SOP's

Isn't it a Boeing CFM thing?
mcdhu

It is completely irrelevant but stems from the starter limit which ECAM covers anyway. Lots of things still done which are a hangover form the old days. ;)

I don't because I see no practical benefit. I know I can attempt a start, dry crank, and second try without exceeding the starter time limit.

If it hasn't started by that point you can guarantee that I want engineering input before trying again.

Our ECAM can't measure consecutive start attempts.

Our limitations: 2 mins on, 15 secs off, 2 mins on, 15 secs off, 1 min on 30 mins off. So in the unlikely event you get to the third start, does you ECAM 'Know' that this is your third start attempt? We have pretty old -320's so maybe the newer ones are smarter.

Engine warm up for our engines is measured from 'at or near idle.' There fore we hack the clock when the starter valve opens then re hack after the second engine is at or very nearly stabilized at idle.

So many versions of a very good airplane flying around, what I just described is how we operate in our little world....

If you have to do a manual start the procedures state that the start be timed. I do it on a normal start so that I know if there is no light off by 45 seconds then there is a good chance that the next sound I here will be a MCW chime. This takes out the startle factor and I can start thinking about letting ATC know that we are going to be on the taxiway a bit longer than they may be anticipating. As someone stated, technique not SOP.

You can exceed the 2 min mark on the crank time with high residual EGT prior to ignition and an aborted start.... It also makes me feel like I have some input without touching something I shouldn't... Unless directed by ECAM :p

If you need to crank with a tailpipe fire you can do it for as long as you like. Noting the time helps engineering decide what to do with the starter unit afterwards.

Starter damage is much cheaper than engine damage.

It could simply be for one's own situational awareness.

Our CFMs should light up within 10 seconds, if not, we place the start lever to cut off.
It will automatically cut fuel if no light up within 15 seconds.
The 10 seconds rule is why I time the start.
It doesn't hurt.

Two people have now mentioned two hours since the previous flight. Is this an IAE limitation? It's a while since I flew aircraft with IAE engines, so it may well have slipped my mind. The magic number for CFM seems to be six hours: if the time elapsed since the previous flight is more than six hours, we can't do single engine taxi, and engines must be at idle for at least five minutes before applying take off thrust.