Looking at Mr. G’s original question and the various answers comments provided to date, I’d like to offer some clarification on a number of the points made.
Firstly, under the conditions referred to, i.e. falling snow at -1 deg C, the aircraft would invariably need to be de-iced, to remove the frozen deposits, then anti-iced, in order to protect the aircraft surfaces until take-off. The majority of the H/A’s in the UK tend to adopt a one-step DE-ICING/ANTI-ICING procedure, using a 75/25 mix of Type II fluid for this operation.
From a purely de-icing perspective it’s not possible to suggest how much fluid is likely to be required for removing the contamination as there are just too many variables. For example, type and amount of snow, OAT, temperature of the structure, fluid type/concentration/temperature, gun/nozzle flow/pressure and the expertise of the de-icing operative, to name but a few... The amount of fluid to be used for this part of the operation will/should therefore be the minimum fluid required (by that de-icing operative) to remove all frozen deposits, under the prevailing conditions.
Now, as hh points out in post #4,the AEA does publish recommended minimum amounts of fluid to be used for protecting the surfaces (anti-icing) of the various aircraft types. Based on this information it would be difficult to understand how an aircraft could be de-iced and anti-iced (in a one-step operation) using significantly less fluid than that recommended by the AEA for just anti-icing.
Mr. G, in post #5 you state that you perform a tactile check before and after de-icing, presumably this is only on those aircraft where the manufacture mandates such a check, i.e. those aircraft types that have experienced significant problems with clear ice, e.g. the MD-80?
Regarding your question on hot water de-icing (post #9), it is permitted down to -3 deg. C but only as the first step in a two-step operation. You can find information on it in Table 2 (page 28) in Edition 25 of the AEA Recommendations at
AEA - Publications
The main problem is that the second step must be carried out within 3 minutes of the first step, so you would need to clear an area of say the wing then protect that area, i.e. anti-ice it, within 3 minutes. This then needs to be repeated over all appropriate surfaces. The other issue is that although an approved procedure, most people associated with aircraft tend to feel uncomfortable with spraying hot water on an aircraft, when the structure or OAT is at or below 0 deg. C.
TTB (post #21), not sure you have a controlled copy but by clicking on the above link you will always be taken to the latest edition...
Mr. T (post #23), it may be worth clarifying that the lower limit of the published time span is used to indicate the estimated time of protection during moderate precipitation and the upper limit indicates the estimated time of protection during light precipitation.
Mr. s (post #24), actually the FAA and TC fund the ongoing work to produce both the generic and brand name holdover time tables and publish the updated information prior to each winter. We in Europe then use this information to base our procedures on.