Survey Report Background Notes
Survey Report Background Notes
The notes found on this page cover those previously found in the Passenger Survey Reports.
One of RPG’s Purposes and Aims is to provide statistical data that enables airlines,
airports and other users to respond to demand. The Departing Passenger Survey
provides comprehensive information on the nature of the passenger market at UK
airports. It supports a wide range of analysis from forecasting air transport activity
through to informing government policy.
While the survey, naturally, has a UK focus, a number of airline operators make use
of survey research to understand better global interline patterns, such as London hub
and spoke activities.
The success or failure of an air passenger survey depends to a large extent on the
help and co-operation of the people on the spot. This involves not only the expertise
of the interviewer and the willingness of the passenger to be interviewed, but also the
attitude of airport staff, airline staff, immigration officers, security officials and others
towards the presence of interviewers within or near their own working areas.
We would like to thank all concerned for their assistance in helping to ensure the
smooth running of the survey projects.
Since 1968 a series of surveys has been undertaken to obtain information about air
travellers and the determinants of the travel market. These surveys have been designed
to obtain information of a kind that could not be collected on a routine basis from the air
transport industry. The surveys have included questions on journey purpose, final and
intermediate surface origins/destinations, means of transport to and from airports, route
flown, country of residence and income. This information is used in assessing the type
of market served by airports and consequently for forecasting air transport demand and
for planning airport facilities.
Cycles of surveys were undertaken at major UK airports in the periods 1970-1972, 1975-
1978, 1982-1987 and 1990-1996. Over each cycle, this gave
95% coverage of the total terminal passengers in the UK.
Following the 1996 survey, which ran at five London airports; Birmingham, Manchester
and four Scottish Airports, demand built up for more regular survey data. After a
consultation process involving all interested parties, it was decided to run a survey each
year at Gatwick, Heathrow and Manchester Airports so long as sufficient sponsorship
was forthcoming. Joining these Continuous Survey airports in 2001 were Luton and
In parallel with the Continuous Survey, the Authority embarked upon a Regional cycle,
which began in 1999. Reports on each of the surveys from this cycle are also available
on the CAA website.
In planning the surveys of air passengers, a principal concern is to derive
maximum value from the information collected, but at the same time to minimize
passenger inconvenience. Therefore, in order to cause as little disruption to passenger
flow as possible, it is necessary to impose a constraint on questionnaire length and
content. To cause minimum inconvenience, most passengers are interviewed whilst
waiting to board their aircraft.
The Authority uses its own field-force, managed by a project team in London. Shifts in
each month are carefully structured so that all scheduled routes and, in most cases, all
flights within a route are regularly sampled.
Several interested parties are consulted over the content of the questionnaires,
including Government departments, airport management groups and airline
management groups. The questionnaires are similar to previous survey
questionnaires in that the same basic questions appear but some new questions are sometimes
included specifically for the co-sponsors of the survey. A copy of a questionnaire used can be accessed on this site.
Referring to the tabulation section of the reports allows the reader to verify many of the
facts and figures quoted throughout this report. Where possible, reference has been
made to the relevant tabulation.
Throughout the creation of these reports, care and attention has been paid to the underlying
data to ensure that an accurate and representative picture of travel movements can be
provided. Where obvious data errors have been identified, (for example, a passenger
travelling by surface means from Cornwall to Inverness Airport to catch a scheduled
flight to Bristol), a correction has been made. There were few such errors identified.
Where interviews have been undertaken, but the passenger has been unwilling or
unable to provide answers to certain questions, the responses have still been included in
the sample, but an “unspecified” code has been used.
Where clarification is required in determining what base population to use, a footnote
has been added.
A typical week was split into 14 sub-categories made up by the day of the week and the
period (morning/afternoon). Interviewing shifts were selected to ensure that, over a 12-
month period, an equal number of shifts were, where possible, in each of the above subcategories.
At all airports only departing passengers are interviewed, previous surveys having
shown that differences in characteristics of arriving and departing passengers were not
All passengers are
eligable, apart from children less than two years of age.
A constant monitor of sampled flights was maintained throughout the year to ensure that
as far as possible all routes, and in most cases individual flights, were covered regularly
throughout the survey.
It was assumed that those passengers who were candidates for an interview, but for one
of a variety of reasons could not be interviewed, had the same characteristics as those
who were successfully interviewed. The overall interviewing success rate for the 2008
survey was 91%.
The interviewing area where passengers or customers are to be found should be clearly
defined to all team members present. A good example may be an airside departure
lounge or gateroom where passengers reside before being directed to a nominated
gateroom to board their flight. At smaller airports, such as Inverness, it may be possible
to interview airport users prior to check-in (Landside).
The interviewing area should be divided into a number of virtual areas, dependent upon
the number of team members available to interview. If there are 4 team members, the
interviewing area should be divided into quarters, however when there are only three
team members, the area should be divided into thirds and so on.
An interviewer will then be assigned an area. It will then be that interviewer's
responsibility to sample passengers who move into their area.
It is of the utmost importance that interviewers do not avoid certain passengers and
show any bias or favouritism to any other groups of passengers. The sampling technique
demands that a representative group of passengers be sampled.
On selecting the first passenger (perhaps to the extreme left of the interviewing area) the
interviewer will run through the questionnaire in the normal manner. On the completion
of this interview, the interviewer will then count three more passengers towards the right.
The third passenger that is counted, assuming that they are eligible for interview will
then be interviewed. Once this interview has been completed, the interviewer will then
count a further three passengers and begin the process again.
Adopting this technique will enable interviewers the freedom to work in a relatively large
area without the need for a counter to indicate the next passenger to be sampled.
Routine checks will be conducted on a monthly basis, to ensure the integrity of the data
The interviewing areas can be redefined during busy or quiet periods directly inline with
the number of team members available to work. As in all other sampling methodologies,
the same passenger cannot be interviewed twice on the same shift.
The sampling and weighting of the surveys was conducted on a route-by-route
basis at each of the survey airports.
Weighting refers to the ‘growing’ of the survey samples to represent actual traffic levels.
A single sample record will correspond to a single passenger interview.
The weighting process is conducted on a monthly basis, with adjustments made initially
within the reporting quarter. Survey data, with provisional weights is then issued to
customers on a quarterly basis throughout the 12-month survey period.
CAA reserves the right to recalculate provisional quarterly weights throughout the survey
period, in some cases reassigned populations against newly validated samples.
The first stage was to list all scheduled routes operated in and out of the airports by
airline and flight number and list all charter routes by airline and destination. The various
airport authorities then provided uplift/discharge figures for each month of the survey.
The routes were initially broken down by airlines into single sector and multi sector
For single sector routes the number of passengers interviewed were added together and
divided into the respective monthly figures to obtain the weights. On multiple sector
routes, weighting was undertaken by the departing flight number. If flights took different
routes on different days as well, they were weighted by the final destination of the
aircraft. Where multi sector and single sector flights were in operation on the same
routes they were divided into separate categories.
In the majority of cases multi-sector routes were unique and therefore weighted
separately. When multi sector routes were combined they were usually for flights
stopping at the same points.
As some flights operated at times when shifts were not run e.g. diversions and most
domestic charter flights, the weighted survey totals are different from those published
in annual statistics as described earlier.
Each survey interview will have it’s own unique weight assigned. As a rule of thumb, a
single survey interview will be weighted in such a way as to represent around 1,000
The Weighting page summarises how scheduled and charter records are weighted, initially
on a monthly basis, before annual and quarterly adjustments are introduced.
Terminating passengers are passengers who arrive at or depart from an airport by
surface modes of transport.
Transfer passengers are passengers who change aircraft at
the airport and have no other reason for visiting the airport. They can be divided into
international-to-international, international to domestic, domestic to international and
domestic-to-domestic Transfer passengers. A Transfer passenger constitutes two
passenger movements; one arrival and one departure. A passenger interlining from one
international flight to another counts as two international passenger movements. A
passenger interlining from a domestic flight to an international flight counts as one
domestic movement and one international movement.
There are two distinct types of international-to-international Transfer passengers -
airside transfer and landside transfer. Airside Transfer passengers do not pass through
immigration, but landside passengers do pass through immigration.
Transit passengers are passengers who arrive and depart on the same flight. These passengers do not
pass the interview point and normally remain on the aircraft.
Terminal passengers are passengers who join or leave a flight at an airport; they include all passengers with the
exception of transit passengers.
The diagram below shows how the classifications are connected.
Where a journey has been broken for a reason other than transit, it is considered to
restart or finish at that point. The following examples illustrate the definition.
“Passenger A leaves home in Swansea, travels to Reading, has lunch and then flies out
from Heathrow Airport."
This passenger's origin would be Swansea as their reason for being in Reading was
"Passenger B, from Watford, travels to Amersham, has a business engagement, then
goes onto Gatwick Airport and flies to Paris.” This passenger's origin is classified as Amersham as her journey has been broken for a
reason other than transit. A transit stop is defined as the point at which a passenger
chooses to break his or her journey to the airport, the main reason for doing so being to
rest, e.g. using airport hotels prior to early morning flights, calling in on or staying with
For the purpose of analysing the origins and destinations within the United Kingdom of
terminating passengers, regions, areas and zones have been defined in terms of
boundaries of, respectively, economic planning regions, counties and district council
areas. The area of residence of UK residents was also recorded using the same zonal
UK and foreign passengers
A passenger is classified as a UK resident if the UK is the country in which he or she has
lived for most of the last twelve months. Those residents in a country outside the UK are
classified as foreign residents.
Journey purpose is classified as business or leisure in the following way.
A further breakdown for passengers on skiing holidays was also included.
Domestic and international passengers
A passenger is classified as domestic if his flight is between two points, both of which
are in the UK (including the Channel Islands). Otherwise he is classified as international.
Modes of transport
Mode of transport refers to the mode of surface transport used to arrive at the airport,
which for outward air passengers, with the exception at Inverness, represents the last
three modes of transport at all sites apart from Inverness.
The occupation group job dictionary produced by the Market Research Society was used
to grade passengers.
The SIC classification is used to code this information.
The mean category limits used to create these tables were trip length (49 days) for trips
over 4 weeks, income (GBP 300,000) for income greater than £230,000 and age (80 yrs)
for passengers older than 74 years.
© Civil Aviation Authority 2012
While every care has been taken to ensure that all figures quoted in this publication
are correct, the Authority accepts no liability for errors made and any consequential
misuse or misinterpretation of the data.
Extracts may be copied from this publication but CAA must be acknowledged as the