Figure: EUR Region, from Eddie's notes.
Regional differences from the ICAO standard can be found in ICAO Document 7030 and your Jeppesen Airway Manual. Both of the sources, however, can be out of date. See International Operations Manual / Regional Introduction for ideas about getting up-to-date information.
As countries around the world update navigation systems and procedures, it becomes increasingly important to speak with somebody who has been to the airport recently or have a contact in country with local knowledge. As we say in the military, there is no substitute for boots on the ground.
What follows comes from the references shown below. Where I think it helpful, I've added my own comments in blue.
[ICAO Doc 7030, §EUR, ¶3.2]
This region is moving from a mix of navigation requirements to the system of Performance Based Navigation outlined in ICAO Document 9613. Current navigation requirements are available on Jeppesen Airway Manual Air Traffic Control pages and Chapter 4 of each region covered by ICAO Document 7030.
[ICAO Doc 7030, §EUR;, ¶220.127.116.11.1]
The term "B-RNAV" was sometimes called RNP-5, before RNP meant more than just navigation accuracy. But the term lives on and you will need it or a system at least as good to fly in parts of the European part of the Middle East.
More about this: Basic Area Navigation (B-RNAV)
[ICAO Doc 7030, §EUR;, ¶18.104.22.168.2]
22.214.171.124.2.1 The provisions in respect of en-route operations, as specified in 126.96.36.199.2.6 and 188.8.131.52.2.7, shall apply to all such operations conducted under IFR on the entire ATS route network as notified by the appropriate authorities in the following flight information regions (FIRs)/upper flight information regions (UIRs): Amsterdam, Ankara, Athinai, Barcelona, Berlin, Bodo, Bordeaux, Bratislava, Bremen, Brest, Brindisi, Bruxelles, Bucuresti, Budapest, Canarias (AFI area of applicability), Casablanca, Chisinau, Düsseldorf, France, Frankfurt, Hannover, Istanbul, Kharkiv, Kobenhavn, Kyiv, Lisboa, Ljubljana, London, L'viv, Madrid, Malta, Marseille, Milano, München, Nicosia, Odessa, Oslo, Paris, Praha, Reims, Rhein, Riga, Roma, Rovaniemi, Scottish, Shannon, Simferopol, Skopje, Sofia, Stavanger, Sweden, Switzerland, Tallinn, Tampere, Tbilisi, Tirana, Trondheim, Tunis (FL 245 and above), Varna, Vilnius, Warszawa, Wien, Yerevan, Zagreb.
184.108.40.206.2.2 The provisions in respect of precision area navigation (P-RNAV) shall be applied whenever RNAV terminal control area (TMA) procedures, excluding the final and missed approach segments, are used. Note.— The carriage of P-RNAV equipment has not yet been mandated in the EUR Region.
While they say P-RNAV isn't mandated yet, it gets complicated . . .
220.127.116.11.2.4 Except as detailed in 18.104.22.168 and 22.214.171.124.2.5, only RNAV-equipped aircraft having a lateral track-keeping accuracy of ±1 NM (2 SD), together with an ability to determine horizontal position to an accuracy sufficient to support the track-keeping requirement and having appropriate functionality and operational approval, may operate under IFR on the RNAV terminal area procedures. Such RNAV equipment is designated hereafter as P-RNAV.
So you must have P-RNAV to operate IFR on RNAV terminal area procedures.
126.96.36.199.2.6 Only aircraft approved for B-RNAV operations may plan for operations under IFR on the ATS routes of the FIRs/UIRs identified in 188.8.131.52.2.1. Aircraft not equipped with RNAV but having a navigation accuracy meeting RNP 5 will be restricted to operations on ATS routes which States may designate within their lower airspace in accordance with 184.108.40.206.2.7.
220.127.116.11.2.7 Until such time as VOR facilities cease to be available, the carriage of a single RNAV system not meeting an average continuity of service of 99.99 per cent of flight time may be approved for B-RNAV operations if the aircraft is also carrying VOR and distance-measuring equipment (DME) equipment.
As of 3 Jan 2014 every country in the Jeppesen Airway Manual, Air Traffic Control, State Rules and Procedures, Europe is listed as WGS-84 compliant, The Jeppesen WGS-84 website, http://www.jeppesen.com/company/publications/wgs-84.jsp, however, lists Greece as only partially compliant. (The web site has been more accurate than the Airway Manual.)
More about this: International Operations / World Geodetic System 84 (WGS-84).
[ICAO Doc 7030, §EUR;, ¶4.2.1] RVSM shall be applicable in that volume of airspace between FL 290 and FL 410 inclusive in the following FIRs/UIRs: Amsterdam, Ankara, Baku, Barcelona, Beograd, Berlin, Bodo, Bratislava, Brindisi, Bruxelles, Bucuresti, Budapest, Casablanca, Chisinau, France, Hannover, Hellas, Istanbul, Kaliningrad, Kharkiv, Kobenhavn, Kyiv, Lisboa, Ljubljana, London, L'viv, Madrid, Malta, Milano, Minsk, Nicosia, Odesa, Oslo, Praha, Rhein, Riga, Roma, Rostov, Rovaniemi, Sarajevo, Scottish, Shannon, Simferopol, Skopje, Sofia, Stavanger, Sweden, Switzerland, Tallinn, Tampere, Tbilisi, Tirana, Trondheim, Tunis, Varna, Vilnius, Warszawa, Wien, Yerevan, Zagreb.
RVSM applies to nearly all of Europe. More about this: Reduced Vertical Separation Minimum (RVSM).
It appears all of Europe has gone QNH.
Transition Altitude / Layer / Level procedures are nonstandard in several locations. For one example of many:
More about this: International Operations / Transition Altitude / Layer / Level.
Air Traffic Flow Management is officially "ATFM" but more often called "Eurocontrol" who are the responsible Central Flow Management Unit (CFMU). They basically handle all flight plans in most of Europe. A good handler can make this transparent to you, but with or without a handler speaking the Eurocontrol language will make life easier.
[ICAO Doc 7030, §EUR;, ¶8.2.1] All IFR flights, including the IFR portions of mixed IFR/VFR flights, regardless of status, are taken into account when measuring demand against ATC capacity. Whenever it becomes necessary to manage this demand, ATFM may be used and departure slots issued by means of calculated take-off times.
[ICAO Doc 7030, §EUR;, ¶8.4.1] ATC is responsible for departure slot monitoring at departure aerodromes. The exact procedures to be followed will depend on the way that ATS is organized at each aerodrome. There are, however, three requirements:
Each country departs in some ways with the ICAO standard and common US practices. Pilots should always refer to the Jeppesen Airway Manual, Air Traffic Control, State Rules and Procedures pages for each country on their itineraries for differences with ICAO Standards, Recommended Practices and Procedures. More about this: International Operations / US versus ICAO.
The following are a sampling of some of the differences, there are many more. You should check the Jeppesen Airway Manual State pages for every country you takeoff, overfly, or land.
About half the countries in the Europe region adhere to ICAO Approach Ban procedures, prohibiting takeoff, continuing en route, starting an approach, or continuing an approach if the destination weather is below minimums. The remaining half either have an exception to the regulation or modify the rule. You need to know the rule for your destination before takeoff. More about: International Operations / Approach Ban.
You can be cleared onto a runway with an aircraft of final, with a conditional clearance. For example, "Behind the landing Air Bus, line up and wait." This is not an exception to ICAO rules, it is a part of ICAO Doc 4444 but I've only seen it in Europe. More about this: International Operations / Conditional Clearance.
European lost communications standards tend to be ICAO Doc 4444 compliant. That should alert all U.S. pilots that they are different from what is used in the United States.
More about this: Abnormal Procedures / Lost Communications.
Some countries have unique missed approach while circling to land procedures, most notably at Amsterdam, Netherlands. At Schipol (EHAM), for example:
[ICAO Doc 7030, §EUR;, ¶18.104.22.168] Line-up instructions may be issued to more than one aircraft at different points on the same runway, taking into account that intersection take-off criteria shall be complied with, provided that:
There are unique procedures at many airports which are close to oceanic areas, requiring an oceanic clearance prior to departure. One example:
Several countries have unique arrival speed restrictions based on altitudes, geographic proximity to the airport, or named waypoints. One example of many:
ICAO Doc 7030 - Regional Supplementary Procedures, International Civil Aviation Organization, 2 2008
ICAO Doc 9613 - Performance Based Navigation (PBN) Manual, International Civil Aviation Organization, 2008
Jeppesen Airway Manual