Guys,
Your question is sensible and the use of reverse thrust should be considered as being specific to the aircraft and runway conditions. It is also different depending on the size of the jet and where the engines are mounted.
My comment is based on what happens when directional control is difficult. I have flown some aircraft where the flight manual recommended not to use Reverse thrust on contaminated ops, although not being on the front line now I do not have copies of this.
On a large aircraft it is different to a small business jet, which is what the comment was in relation to.
On a small jet with tail mounted engines the use of reverse thrust can cause a pitch up moment which takes pressure off the nosewheel. Also in any crosswind or uneven braking between the mainwheels there can be directional control issues which will be made considerably worse by using reverse thrust.
Eurocontrol advice about landing on contanimated runways states;
Directional Control
Effective directional control, on a contaminated runway surface during landing, requires that all wheels are firmly on the ground without undue delay and that the control column/sidestick is then promptly centralised both longitudinally and laterally, so as to avoid inducing asymmetric main gear wheel loading and achieve adequate nose landing gear wheel loading. However, the main initial means of directional control during the landing roll is likely to be the rudder, which on most aircraft types will remain effective until around 80 KIAS - sometimes even less.
If directional control problems are experienced at high speed, then it is normally recommended to cancel reverse thrust/pitch until satisfactory control is regained. If autobrake has been selected and is producing differential brake release which is aggravating directional control, then selection of manual braking is usually recommended with full brake pedal release on one side being a usual way to achieve this quickly. Manual differential braking will usually need complete release of brake pedal pressure on one side.
Once rudder effectiveness is lost at lower speeds, directional control difficulties on a contaminated surface may increase, in contrast to what would be expected on a landing roll on a normal friction surface. This is because:
The effects of even minor differential manual braking are likely to be greater;
Thrust Reversers/Reverse Pitch are likely to be more de-stabilising;
Reduced nose landing gear wheel adhesion directly limits both steering input options and the usual directionally-stabilising effect of the nose landing gear;
Yaw effects arising from any differential braking effectiveness are exaggerated.
Remember my comment was about the use of reverse thrust in small business jets and not type specific.
MM