Specifically what titles/positions cannot fly on the same flight, or how many (% or #) of the executive management team are allowed to fly together.
A: We do not have survey data on the specific precautions taken by organizations, but certainly many corporations have developed policies limiting the number of corporate officers that may travel together on the same flight or other particular transportation method. The specific needs vary by organization, according to size.
Often policies will prohibit the CEO, COO and chairman of the board from traveling together, or permit only two of the three to travel together. The key is for your management team to figure out if you lost more than one key executive manager at the same time how would it impact the business. There have been instances where businesses have suffered as a result of losing multiple key executives during the same air travel. With regard to company officers that may travel together, two or three are common limits. Likewise, policies may set limits on the number of associates that may travel together. Typically a Board of Directors will set the limit based on their comfort of knowing there is always an alternative executive who can continue to run the organization.
The NBTA (formerly the Institute of Business Travel Management) published a guide a few years ago called Emergency Guidelines and Procedures for Corporate Travel Programs that recommends such a policy, though does not prescribe specifics. You can find it at http://www.nbtafoundation.org/NR/rdonlyres/A341F2EC-374C-4D3C-BBA9-E246C64FB374/0/Kroll_Crisis_Plan.doc.
The National Business Aviation Association has a sample policy air transportation policy here: http://www.nbaa.org/basics/SampleAircraftUsePolicy.doc.
It is prudent for any organization to consider developing such a policy.