Talk:Boeing 717

Problems with recent edit (reverted and re-reverted)

"With the 1997 merger taking prior to production..." - grammatically incorrect (taking place? happening?)

"...design range of 2,060 nautical miles [nmi] (3,820 km; 2,370 mi)." -- nautical miles was already spelled out and linked by the unit conversion template, what is the nmi in square brackets even doing here?

In the lead, "broader DC-9 family" is redundant, making the lead longer for no good reason. (if it is a product family, of course it includes other models).

Fbergo (talk) 00:44, 15 June 2023 (UTC)

1) Fair point. Changed.

2) nmi is a rare unit of measure outside of aviation, for a generalist encyclopedia I felt it helpful to clarify the abbreviation at first usage.

3) Agreed it’s a bit clunky, but it’s also the way most of the DC-9 pages are worded. RickyCourtney (talk) 04:51, 15 June 2023 (UTC)

Infobox image

The lighting on the current infobox image is a bit flat. I propose switching to a sunnier image:

File:Delta Boeing 717-200 N930AT BWI MD2.jpg 4300streetcar (talk) 17:19, 18 June 2025 (UTC)

• This image above is about the same as the current image in Infobox now except opposite side of plane and clearer sky. Both images seem fine to me. -Fnlayson (talk) 17:25, 18 June 2025 (UTC)

Maximum speed / cruise speed discrepancy calculations

@DaveReidUK

Currently the maximum speed listed in #Specifications is lower than the cruise speed listed there, which is obviously a problem.

Boeing's technical characteristics (current cited as a source) and Delta's spec page (not currently cited) list 504mph as the cruising speed. However, the cited FAA Type Certificate on page 66 lists the V_MO (maximum operating speed) as 340 knots KCAS (391mph) at all altitudes (sea level-37,000ft). That is currently listed as the "maximum speed" in specifications.

There appears to be a discrepancy, but KCAS does not account for changes in air pressure due to altitude, so we need to convert KCAS into true airspeed at cruising altitude to resolve the discrepancy. I'm unfortunately not familiar with the calculations to do this - can someone convert 340 knots KCAS to true airspeed at 37,000ft?

I did punch the numbers quickly into Aerotoolbox, and 340 knots KCAS is 581 knots (669mph) at 37,000ft, so we can use this stat to resolve the discrepancy if the calculations can be validated. 4300streetcar (talk) 17:33, 18 June 2025 (UTC)

The two values are not at all inconsistent, provided one understands (and explains to the reader) what they mean.

Quoting "581 kts TAS at 37,000 ft" would definitely be wrong - that's over Mach 1! The 717's Mmo is M=0.82. DaveReidUK (talk) 17:56, 18 June 2025 (UTC)

The origin of the issue is that Wikipedia's "one-size-fits-all" approach to aircraft specifications is inherently incompatible with modern (and not-so-modern) airliners.

The nearest thing to a "maximum speed" for a jet airliner is the TAS at the "crossover altitude" (the altitude at which the TAS matches both the Vmo and Mmo). Above this altitude an airliner cannot legally fly at Vmo and below it cannot fly at Mmo.

So the best solution would be for the "Maximum speed" tag to document both the Vmo/Mmo limits from the TC (with Vmo in KCAS or KIAS, depending on the aircraft certification), accompanied by the corresponding TAS (speed through the air and, in the absence of any wind, over the ground) that would result under standard conditions, shown in the usual mph, km/h and kn units, together with the altitude at which those speeds apply.

Those values for the 717 would be 340 KCAS M=0.82 corresponding (at the crossover altitude of 26,000 feet) to 566 mph 911 km/h 492 kn.

As for "Cruising speed", that’s not normally documented in the TC, so any airline published value would do, and obviously Vmo/Mmo don't need to figure here.

Comments welcomed from all who have been keeping up! DaveReidUK (talk) 16:48, 19 June 2025 (UTC)

Template:Tq The current specs system is heavily based on the standard used by a vast majority of aviation encyclopedias, including Janes, which seems to be working perfectly fine for them. For transparency, DaveReidUK has been one of several vocal proponents of specs tables, which blatantly violate the consensus outlined by WP:AIRSPECS on about a few dozen airliner articles. A lengthy discussion about this can be found here and at the associated RfC.

It should probably be noted that there is only a single named major variant of the Boeing 717. While the previous table treated the high gross weight certification standard as a distinct major variant, I have yet to see any reliable sources that make such a distinction, including the FAA TCDS. - ZLEA _T\^C 17:51, 19 June 2025 (UTC)

I should have known we could rely on you to conflate this with a completely unrelated topic.

How maximum speeds are displayed is equally applicable to whether a single variant is specified in a list, or multiple variants in a table. The debate over the latter has no relevance whatsoever.

Do you actually understand anything at all about this issue? DaveReidUK (talk) 18:16, 19 June 2025 (UTC)

Well then, may I ask what you meant by Template:Tq if you weren't referencing your preference for specs tables or your or the perceived flaws in the current specs system you have been talking about in those discussions? - ZLEA _T\^C 18:28, 19 June 2025 (UTC)

See the above discussion, and the 717 article as an illustration.

The issue is specifically the portrayal of maximum speeds (aka airspeed limitations).

Simply listing a single value in various units gives no information on what it is (or should be) derived from, ie Vmo/Mmo and the corresponding TAS values at the crossover altitude (see my example above). Very few Wikipedia airliner articles (whatever format the spec takes) appear to have numbers that are consistent with the TC airspeed limits.

For obvious reasons, this only affects civil certificated jet airliners, hence my reference (which you misinterpreted) to "one-size-fits-all". DaveReidUK (talk) 18:46, 19 June 2025 (UTC)

My apologies. Perhaps I'm a bit on edge after one of the other pro-table editors created a (now deleted) attack page against me. I agree that this appears to be an issue. Perhaps it should be brought up at Template talk:Aircraft specs so we can find a solution. - ZLEA _T\^C 18:57, 19 June 2025 (UTC)

Apology accepted. Yes, that sounds like the best place to discuss it. TBH, I'm not even sure whether the current template may actually accept that additional information already. DaveReidUK (talk) 19:27, 19 June 2025 (UTC)

Template:Tq I think it can be done. If I understand the issue correctly, I believe there is a simple fix for it. I unfortunately am not in a position to analyze the template code right now, so I won't be able to propose a change until I get back to my laptop later tonight. - ZLEA _T\^C 19:39, 19 June 2025 (UTC)

DaveReidUK If I understand this correctly, you want to add the altitude at which the airspeed is measured to the specs? If it's as simple as that, then the template doesn't need any changes as you can add the altitude via the corresponding "notes" parameters. If there's more you want to do with it that might require changes, the template's code is simple enough that I could propose said change with the template's sandbox. - ZLEA _T\^C 04:38, 20 June 2025 (UTC)

Yes, certainly the applicable altitude needs to be stated. In order for the "Maximum speed" value to be a true maximum speed (i.e. the fastest achievable airspeed under standard conditions), that altitude needs to be the "crossover altitude" (the altitude at which the aircraft hits both the Vmo and Mmo limits, normally stated in the TC).

So the changes would be firstly noting the altitude criteria (rather than it looking as if it's an arbitrarily chosen value) and secondly explicitly stating the Vmo and Mmo limits (with the necessary citation), so as to allow a reader to verify the resulting Maximum TAS values, should they so desire.

So, format-wise and taking the 717 as an example, something like: "Maximum speed: (Vmo=340KCAS, Mmo=0.82 at 26,000 feet) 566 mph 911 km/h 492 kn"

Alternatively, if we think readers might be confused by two different speed types (CAS and TAS) in the same line, Vmo/Mmo could become a separate parameter in the Specification template, although of course that's a bigger change from present. DaveReidUK (talk) 07:38, 20 June 2025 (UTC)