There are plenty of factors that would have to be taken into consideration with a situation like this. I would suggest that unless the incapacitation was life threatening then potentially a Commander may choose to continue the flight if he deems it safe to do so, so to me the implication here is that the First Officer was seriously unwell. Had it been the Commander who had been incapicated the situation would be more critical due to the experience level of the remaining pilot. Certainly the key regardless of the severity of the illness would be not to rush any diversion, as the safety of everybody on board takes precedence over the speed of the arrival. No point in getting to an airport 3 minutes earlier but arrive in a ball of flames and the airframe in several pieces.
In my mind if this situation had happened to me I would be looking at how severe the incapication is, can we continue to destination or return to base, how much care can be provided on board for the sick crew member, how is the weather at any potential diversion airfields, am I familiar with any of the nearby airfields, are there facilities more suited to the situation at a particular airfield, is there an airfield nearby that the company has nominated as potential diversion option, do I have the approach plates for that airfield. Other considerations may be whether we can easily disembark the sick passenger (does the airfield have steps that will reach the entry doors), will there be suitable ground handling for the aircraft once the ill crew member has left the aircraft, will I need to refuel and can I do so etc etc etc etc.
So without knowing all the causal factors on the day it would be impossible to say what the best course of action would be given that set of circumstances. I cannot see any reason on the face of it why CDG
would be the best option for the crew on board, Amsterdam generally has a better reputation in my mind at least as being a potential medical divert, the airfield is better equipped to cope with a medical emergency (I have never done it though, feel free to beg to differ!), it is also closer to the departure airfield whether presumably the crew is based, this means that it would be easier to source a replacement crew member if the existing crew were within hours to continue the flight and also the ill crew member would be closer to home. The Captain may be familiar with Amsterdam or could even be Dutch. From FL370 in a normal descent an airliner would need around 120nm for a normal idle power descent to an airport, factoring in collecting approach plates for the given airport (and the fact that they may have to be sourced by a cabin crew member as the incapacitated crew member would be unlikey be in a fit state to find them) and prepare for the approach which could take 5 or so minutes, (5x8nm/min = 40nm) then Amsterdam is just about the perfect distance away to choose as a diversion airfield.
Reasons for not going to CDG
? To make the descent the aircraft would continually need to be turning to maintain proximity to the airfield which would add a workload to the pilot, ATC would probably be extremely expedient in offering solutions to get in which greatens the potentially for rushing to meet the clearances received. I've never done it but I expect they'd give you descent pretty quickly and give radar vectors to commence an approach immediately. Obviously a competent pilot on a good day would ask to hold until they had set up the aircraft for an approach and landing but the added temptation is there and that is not particularly helpful. As far as I am aware CDG
is a complicated airfield to get round and is it further from a hospital than AMS
? Maybe.. The Captain may never have been there or he had been there and had one or more bad experiences that may put him off choosing it. The weather may not have been as useful (Thunderstorms in the area, strong winds and crosswinds).
In any cases, an immediate diversion I would want to know the following pieces of information immediately: Is this airport open, is the runway long enough, is the weather good enough. If those are satisfied, we can use it if need be. If we are not completely committed to diverting to that particular airfield either because there are others available or the situation is not absolutely critical then all those other factors come in to play.