Does a request for a Pop-Up IFR clearance constitute filing a flight plan? Introduction

Pop-up IFR clearances are an accepted way to transition from VFR to IFR flight by obtaining an IFR clearance. They are well documented from a controller's perspective in this Tarrance Kramer article appearing in AvWeb and from a pilot's perspective in this Rick Durdan article appearing in AvWeb.

These related Aviation.SE questions also address the topic:


How do you request a “pop up” IFR clearance?
How do you open and get a IFR clearance while in the air?
How should I request an IFR approach at the end of a VFR flight?


Clearly, this is an accepted way to obtain an IFR clearance; I have made use of the option myself plenty of times.

Legal Background

Now, pop-up clearances are often requested and granted with no previously filed IFR flight plan which, on the face of it, would seem to be in violation of 14 CFR 91.173 which states (emphasis mine):


  No person may operate an aircraft in controlled airspace under IFR
  unless that person has—
  (a) Filed an IFR flight plan; and
  (b) Received an appropriate ATC clearance.


14 CFR 91.169 gives the information required for filing that required IFR flight plan, which states, in part (emphasis mine):


  Unless otherwise authorized by ATC, each person filing an IFR flight plan must include in it the following information: [...]


(I omit the long list of actual information)

The Question

The first part of my question is:


Does a request for a pop-up IFR clearance constitute filing a flight
plan?

Is there an unwritten (or perhaps written) understanding that the request for the IFR clearance constitutes filing a flight plan to the extent required by 14 CFR 91.173?


The second part of my question is:


Why is the full list of information required
for filing an IFR flight plan not required, in fact, of a pilot
requesting a pop-up IFR clearance?

If ATC issues an IFR clearance without this information, is that a tacit, but legally valid, authorization to exclude the information otherwise required by 14 CFR 91.169?


Is all this actually codified somewhere that I am not aware of?
I think Porcupine911 nailed the first question perfectly with the reference to JO 7110.65W: A "pop-up" IFR clearance counts as filing an IFR flight plan.
ATC considers it an "airfiled" flight plan (VFR-to-IFR), and the controller talking to you will take at least the bare minimum information necessary to enter you into the ATC system and generate a flight plan / strip for your aircraft.



Your second question is a little more complicated, but the short answer is that pop-up IFR clearances aren't "tacit authorization to omit information required by 91.169", but controllers are busy people and don't have time to key all that into the computer when they're supposed to be working traffic.  

The longer version is that what you probably should be doing to get an IFR clearance in-flight is calling the local flight service station over the radio and air-filing your IFR flight plan with them, then checking in with ATC (who will have all the information Flight Service took from you and entered into the computer, without having to tie up their frequency interrogating you for it). 

The FAA (or at least the ATC organization) is not without a heart though: They understand that if you're calling them for a pop-up IFR clearance it means you're in a bit of a situation (like IMC closing in on you with no good "out" that will allow you to remain VFR) and you need to get into the system before you hit the ground, a building, or another aircraft.
Giving the controller the bare minimum skeleton of a flight plan allows them to get you into the system and under positive ATC control to ensure you're operating at a safe altitude without any traffic conflicts, which satisfies the first of the three ATC operational criteria ("Safe") -- the other two (Orderly &amp; Expedient) are a lower priority and can be dealt with later.