Selecting the correct aircraft is a complex process, involving a multi-disciplinary team of people and skills with considerable knowledge of the business.  At a fundamental level, buying aircraft is necessary to support the basic strategy of the client. Typically, the aircraft will be purchased for either replacement or growth needs; replacement for when an aging aircraft begins to incur higher operating costs, or to introduce new technologies, whilst growth will trigger requirements for increased range, higher payloads and specific performance capabilities.


A key issue in appeal is that the airframe should be able to offer a good degree of flexibility for reconfiguration. Aircraft can be operated within a range of mission profiles by many different owners during their useful lifetime. the evolving requirements and tastes will dictate interior arrangement and the overall feel of a cabin, minimizing the complications of reconfiguration therefore becomes very important factor to consider.
Traditionally, aircraft selection decisions are dominated by the range capability of the products under evaluation. This was because range was often a limiting factor for clients wishing to expand their global reach. Today’s aircraft have much greater range capabilities and so this element has diminished in significance. The current offerings from today's manufacturers include products with a capability of over 7’500 nautical miles’ range. meaning that the vast majority of the world’s city-pairs can be served non-stop. 
However, many clients do continue to place the relevance of range when comparing aircraft types. There are sound reasons for this. For example, the future value of an aircraft is partly determined by its range ability. Operators of very early production models can often be disadvantaged, as take-off weights, and therefore range, are always limited until improvements can be worked into the design. It is very common  for the first version of a type offered with a conservative payload-range envelope. This is largely because the structural integrity of the airframe must be proven.
As experience with the airframe grows, so does the aircraft manufacturers confidence in releasing increases in take-off weight that had been retained as margins in the original structural design. During the life of the aircraft design in service, it is typical to expect several evolutions of the weight, each one enhancing the maximum range possible. Such developments are often accompanied by many other changes to the design as well, such as increased fuel volume and other product enhancements.
Using an aircraft with the maximum range may not be the most appropriate solution if that range is not strictly required. The same can be said for economics. Of course, it is in the interests of the client to minimize costs, but there are some additional considerations that can result in higher costs being incurred in order to ensure a better overall result in the longer term. 
The right economics will also be judged according to how forgiving the aircraft type will be in certain areas of the cost breakdown. For example, if a client will be using airports where landing fees are relatively high, then it will be important to place more emphasis on the take-off weight of the aircraft in the evaluation. Some aircraft types are more efficient, or productive, in terms of weight per unit of payload than others. 


Flexibility has become a key requirement - this is the challenge of matching a physically inflexible aircraft with an owners requirements that will experience constant change.
Airliners are able to offer a greater degree of flexibility. The large interior floor space and volume provide more opportunities in terms of interior layout, A key question is whether the inherent design of the cabin allows cost effective and rapid reconfiguration in order to address the clients future needs.
The issue of operational versatility can be seen from the perspective of the longer-term design, customers are now far more responsive to business and lifestyle changes than ever before, with re-configurations, and modifications of the cabin now commonplace.
Another aspect of flexibility that should be considered, is the degree to which the aircraft design offers alternative interior options. For example, it is always beneficial to be able to configure the aircraft for both private and commercial operations, different passenger counts and alternative interior layouts. 


Between the different airframe, engine and interior suppliers it is typical to expect different philosophies in design and maintenance, and different approaches to customer service and product support. Customers may pursue a multi-supplier philosophy for strategic reasons, such as spreading risk and encouraging more competitive offers from the manufacturers. Or in cases where competing manufacturers do not offer aircraft in every market category.
Following the decision to acquire a particular aircraft type, it can be beneficial to stick with that particular technology standard as the clients fleet develops. Besides the benefits derived from economies of scale and progression along the learning curve, there are synergies to be reaped in many aspects of the customization process, spares investment, tooling, training, and day-to-day operations. 


The aircraft evaluation contains the assumptions under which the manufacturers asses the interior configuration, payload capability and weight of their aircraft according to the customers requirements.

When these parameters have been fixed the manufacturer will simulate the performance of the aircraft on a set of routes in order to establish take-off performance at airfields, fuel consumption and payloads.

In addition, the evaluation may require economic and financial calculations. Fixing these assumptions is one of the most critical areas in the planning process. 


The conditions under which aircraft are compared do not necessarily reflect the conditions under which they may be operated. Indeed, it is rarely the case that the interior configuration used in an evaluation reflects the layout of a delivered aircraft. This is mostly because it is just not possible to assess with any precision how the aircraft will be assigned onto a network, which may itself evolve between the evaluation phase and the final delivery. 
During the early phases it is sensible to use a degree of conservatism into the evaluation. It does not make sense to be overly optimistic in the early stages of the evaluation as this can only serve to deliver unpleasant surprises later in the process. However, the assumptions should not be too conservative either, as penalties on payload, weight and fuel burn will only serve to give the impression that the aircraft is inadequate. 
Where an aircraft being considered is a totally new design, it is prudent to add more conservatism to some of the study parameters. However, generally it is wise to apply the same conditions for all aircraft under consideration avoid introducing bias. 
The manufacturers will push for assumptions that enable aircraft to be marketed in the best light and will be reluctant to accept parameters that unduly penalize the performance or economics of the aircraft. the manufacturer should be allowed sufficient flexibility to introduce elements of value that might otherwise remain hidden.
When compiling the evaluation it should be understood that the content may be applied not only to new-build aircraft currently under production, but to used aircraft that are already in service, and aircraft still in the project stage for which the level of data will be reduced. The degree of conservatism applied will be different in each case. 


The evaluation must provide information concerning the numbers of desired guests and staff seating. toilets, galleys, storage, and arrangements for sleeping and rest areas. The derivation of the Layout Of Passenger Accommodation, or ‘LOPA’, is a vitally important exercise as the configuration drives the weight of the aircraft, the performance, payload capability and economics. Should adjustments be made at a later stage the knock-on effects could be significant. 


Details the operational items including passenger weights (including baggage allowances), preferences for carrying passenger baggage and cargo, plus cargo and fuel densities. 


The customer has to be assured that the aircraft can be handled at all of the airfields in the current and future network. The manufacturer must supply aircraft dimensions, pavement loading limits, ground maneuvering requirements, ground support equipment that is specific to the aircraft type and data concerning the weight and balance of the aircraft. Most of these data can be found in the Airport Planning Manual for the aircraft.


This is an opportunity for the client to indicate any specific requirements in how the economic and financial analysis should be conducted. For example, the customer may wish to see numbers relating to an average block time or average utilization.
The Aircraft Selection Criteria and the Aircraft Evaluation documents, form the core of the Request For Information (RFI) that can be sent to the selected aircraft manufacturer. It is typical to give the manufacturers a target date for submission of their responses. However, as the RFI is not a formal document and the manufacturers are under no obligation to respond by a set date, sufficient time should be allowed, placing undue pressure on the manufacturers at this stage is counter-productive as generating a thorough and accurate set of data involves numerous specialists. 
As the manufacturers are invited to present their results, they will augment their responses with marketing messages to support their products. Manufacturers should be encouraged at this stage to offer additional ideas and concepts, especially as they will have access and analytical tools that are designed specifically for fleet planning purposes.
It would be unusual if manufacturers responded perfectly to the RFI at the first attempt. Compliance is not a contractual matter, so deviations may be accepted providing efforts are made to correct any changes to the assumptions to all manufacturers equally. Keeping track of such changes is important to maintain a level playing field. 
A usual consequence of the first round of results is that the manufacturers would be asked to refine their RFI responses. Once a satisfactory set of data has been provided from all the manufacturers the client can elect eliminate the unsuitable aircraft. 


This is often the largest section in the evaluation Here, would typically contain instructions for the calculation of the take-off, temperature conditions to be applied, and specific dimensions of airfields to be considered in the analysis, including their ambient conditions. For route performance would contain information concerning the flight profile, a list of routes to be analysed along with distances to be used and the wind conditions to be applied.


The Request For Information is used as a structured method of channeling the clients questions about the product. The aircraft manufacturer’s sales team will typically consist of the Sales Director and Marketing Analyst, augmented by specialists according to the specific need, up to the point where a proposal is prepared.

The requests at this stage usually comprise a mix of technical, operational and support issues. The RFI, whilst not a contractual document, is a critical step in communicating a common set of ground rules under which the performance and economics of the aircraft under consideration may be estimated, the RFI phase is where the manufacturer and client agree on a common set of aircraft selection criteria to be used.  


When an RFI is issued it is recommended that a deadline for the delivery of the response be determined. Where products are available from competing manufacturers it is important for the client to encourage competition by issuing an RFI to all potential suppliers with the same questions and the same deadline.
It is sometimes the case that manufacturer responses to an RFI are not satisfactory the first time around. manufacturers can push for changes to the assumptions in order to present an aircraft in a better light. it is possible for requirements to be adjusted and revisions added to the assumptions and documentation provided. It is critical that all changes incorporated into the RFI during this phase are shared throughout the process. So, its is typical to perform at least one iteration in order to ensure that results from all the manufacturers are as accurate as possible. This phase may take several months, during which the manufacturer may make several visits to the client to submit marketing presentations and aircraft performance data. 


At this stage the manufacturers should have fully answered The RFI and the client should be satisfied that data are both accurate and fair. The submission of the RFP represents the start of the full campaign, where milestones need to be set on both sides and where priorities need to be identified.
It is usual for the dialogue between the manufacturer and client to intensify during the preparation of the RFP response. Within the clients team will be the responsibility for managing the coordination of all contacts between the manufacturers and appropriate representatives. Engagement will take place at a number of levels. Working level contacts are therefore vital in order to ensure that assumptions are being correctly adhered to and that all relevant areas are being addressed. Meetings and presentations are important in order to inform decision makers of the evolving situation.
RFPs issued to the aircraft manufacturer will at minimum contain the following elements:
  • Regulatory status of aircraft types
  • Expected payload and range capability
  • Delivery dates for firm order
  • Expected aircraft utilization
  • Product support requirements
  • Expectations of financing support 
  • Guarantee requirements and remedies
  • Levels of reliability
  • Peripheral investments
  • Expected response date
  • The desired period of validity of the commercial offer
It may be the case that RFPs are sent additionally to the engine manufacturer to cover an engine support package. In this case the RFP to the engine supplier would include additional elements, such as: 
  • An expectation of concessions to cover initial provisioning and tooling
  • Required documentation
  • Guarantees to cover fuel bum, delays, and various engine parameters, such as in-flight shut down rate, shop visit rate and associated costs 
  • Details of an engine condition monitoring program
  • Confirmation of which service bulletins are not chargeable during guarantee period
  • Listing of life limited parts, warranties and costs
  • Details of engine repair and overhaul requirements


Once all the responses are delivered, the clients representatives will be required to extrapolate, digest, analyse, sift and interpret the data, then compile internal material to communicate further with the owner.  
Negotiations between the client and the manufacturer would start at this point. The contractual negotiations take a prominent role, aided by specialists involved in guarantees, option selection, financing, spares provisioning, and training. It is also important for the customers representatives to manage the communications with the engine manufacturers and vendors of equipment in order that negotiations take place and selections can be made. 
Once the client has deliberated and extracted what is believed to be the best offer from the suppliers, a decision can be made. In the Event of a positive decision a Letter of Intent (LOI) or Memorandum of Understanding (MOU) would be signed in order to secure delivery position. It is usual that a refundable deposit would be made at this point.


From when the signatures have been obtained on the contract, up to the point where the aircraft is delivered to the client. The first activity would be to organize kick-off meetings to plan for the entry into service, the specification review and cabin definition. Then, a series of key conferences would be arranged to address the initial provisioning of spare parts, maintenance planning, and training and general support-related issues. Naturally the manufacturer plays a significant role in managing the timetable during this period. In the course of the 12-month period before the aircraft’s first delivery both the Aircraft OEM and Modification Center will be expected to support the following deliverable's: 
  • Preparation and delivery of manuals and technical publications
  • Development of the maintenance Planning Document
  • Creation of the Minimum Equipment List (MEL)
  • Determination of initial provisioning of spares, tools, and their delivery
  • Organisation and execution of training for pilots, maintenance personnel and cabin crew
  • Set up access to online E-Services of equipment suppliers
  • Establish the warranty process. 
  • Install the on-site support team
Well after a sales campaign has been concluded, the manufacturer’s sales and marketing personnel maintain their involvement with the clients representatives in order to provide continuity of the relationship. The manufacturer has an interest in ensuring that deliveries are properly managed and will obviously seek further opportunities to extend the order book. Feedback from the client in terms of experience of the aircraft in operation is also a vital part of the relationship.