the "Priority Express"

[lakeroadster]

I acknowledge that there is ample room for interpretation here. That said, I nevertheless take issue with the definition above, for two reasons.

1. The first and second sentences contradict each other in the case of a nozzle blow-out. In my experience, both first and second hand, after the nozzle is blown, the propellant burns slower than planned, by quite a lot. Which should be expected, assuming the propellant's burn rate exponent is positive.
2. I reject the final sentence, that an ejection failure is also a form of CATO, since that happens long after take-off.

All of these things certainly merit MESS reports.

I can't find a reference, but I have long "known" that the term has been around referring to instances of unplanned rapid (and usually pyrotechnic) disassembly, dating back to many of these guys; events on or barely off the pad:

I'm guessing that's why MESS (Malfunctioning Engine Statistical Survey) was used instead of CATO.​

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But with all due respect Joe, your getting way too picky here. Keep It Simple Silly, the term is slang, and in my mind it's interchangeable with Malfunctioning Engine Statistical Survey (MESS).​

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If the motor has an issue and the boundaries of it's containment fail, that's a CATO.​

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And if there's no ejection charge... that's a CATO also. Now... you have to prove the ejection charge scenario... might be a slippery slope.​

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[Ronz Rocketz]

darn, Neil beat me to the same quote (although from different source.). Interestingly Wikipedia has a slightly different interpretation which is however NOT sourced (so much for the Internet in general or Wikipedia specifically being the repository of all knowledge.)

A PRACTICAL definition may be: Motor failure that would justify a MESS report and likely spur manufacturer to replace the motor and possibly the rocket.

For black powder and single use composite motors I would say that a failure of the motor walls would qualify, so
1. the casing
2. Significant portion of nozzle
3. Premature failure of forward wall (basically a near instantaneous combustion of the whole propellant mass at ignition that blows out the front, usually either on the pad or a few feet above it.

I don’t fly reloads, so don’t know if this applies to failures of forward and aft closures.

Interesting that while the origin of the specific initials C. A. T. O. is debated, the assumption that it refers to “CATASTROPHE” seems universally accepted. If so, seems actually to frequently be wrong.

True, most if not all CATOs result in failed (or at least far from nominal) flights.

True that SOME CATOs destroy or nearly destroy the rockets.

But seems like many if not most CATOs do little or no damage to the rocket. Not that I am recommending them, but some are darn entertaining (I am thinking of a certain A10-0 Twin Factor flight with @kuririn snd @Ronz Rocketz a year or so back with three or four CATOs. Retrospectively might not have been the greatest idea to CHAD stage 4 motors to a two stage rocket, but we didn’t expect the majority of motors to CATO. Anyway, no rocket or property damage, no physical injury although may have stirred up my Post Iraq deployment PTSD for a moment.)

Anyway, I’m not convinced that all CATOs truly qualify with anyone’s definition of Catastrophe, despite that seeming to be the one universally accepted origin of the word.

Since the word is used so much and isn’t going away, I’d describe it as a post ignition containment failure of one or more motor walls (casing, nozzle, or if well prior to normal burning of delay, forward wall). Damages range from injury to reputation of the motor vendor to destruction of rocket, personal injury, and/or property damage.

I don’t know what you’re talking about.