May one drink coffee brewed by a gentile in a Kosher vessel with Kosher ingredients? Is coffee considered Bishul Akum?
Kashrus of the coffee powder, and pot: Drinking coffee made by a gentile poses several Kashrus concerns such as a) Is the coffee powder Kosher? b) Was non-Kosher milk added to the coffee pot within the past 24 hours? c) Is the coffee pot washed in hot water together with non-Kosher ingredients and has it been washed within 24 hours of the current use? d) Bishul Akum; e) Drinking in a party of gentiles. Below we will address only the concern of Bishul Akum. In general, all non-flavored coffee is considered Kosher, and hence if one knows that the coffee pot is used only for plain coffee [no milk] and is washed alone without other utensils, then the only remaining concern is Bishul Akum. Some say that coffee pots on planes fulfill the above conditions, and hence its only remaining issue is of Bishul Akum, which will be addressed below. However, others have testified of Kashrus concerns with the coffee pots.
Bishul Akum: Some Poskim rule it is permitted to drink coffee that is brewed by a gentile, and it does not contain the prohibition of Bishul Akum. Other Poskim rule it is forbidden to drink coffee that was brewed by a gentile due to the prohibition of Bishul Akum. Furthermore, some Poskim rule a Torah scholar is not to drink coffee cooked by a gentile, even if it is not prohibited due to Bishul Akum. Other Poskim however argue that it is not necessary today for a Torah scholar to be stringent in this matter. Practically, one who desires to be stringent, should be stringent upon himself, while one who desires to be lenient is not to be protested.
Practical suggestion for airplane coffee: In order to avoid any Kashrus issues, it is suggested that one use a disposable, or glass cup for one’s coffee, and likewise get hot water from the main tank, rather than the coffee served in the coffee pot.
 See Birkeiy Yosef 113 Shiyurei Bracha 3; Pischeiy Teshuvah 114/1; Kaf Hachaim 113/21
 Rav Heinman of Chof Kei and Rav Belski of OU allows drinking plane coffee.
 In one case the flight attendant admitted to heating bacon in the pot and then washing it out for use for the coffee; In another case they said they randomly switch off pots used with milk.
 Radbaz 637; Peri Chadash 112/17; 114/6; Yaavetz 2/142; Beis Yehuda 91; Yad Efraim 114; Beir Oshek 105, brought in Gilyon Mahrsha 113; Teshuvos Bach 155 is stringent upon self, but does not protest others; Mahrikash 114; Bnei Chayeh 145; Darkei Teshuvah 113/2; Zivchei Tzedek 113/15 that so is custom of Bagdad; Ben Ish Chaiy Chukas 16; Chochmas Adam 66/14; Aruch Hashulchan 113/22-23; Shearim Hametzuyanim Behalacha in name of Chasam Sofer; Yechaveh Daas 4/42
 The reason: As coffee is mainly made of water, and water can be drunk plain, and is hence exempt from Bishul Akum. [Peri Chadash ibid]
 Kneses Hagedola 113/17; Arizal in Nagid Mitzvah, brought in Kneses Hagedola, Kaf Hachaim ibid [Kneses Hagedola and Kaf Hachaim ibid learns that according to Arizal it is forbidden, however other Poskim learn the Arizal was only stringent to himself]; Panim Meiros 2/62, brought in Pischeiy Teshuvah 114/1; See Shevet Halevi 2/44; 5/93
 The reason: As coffee is not viewed as plain water, and it is fit to be brought to a kings table. Therefore, it shares all the prohibitions of Bishul Akum. Thus, a Baal Nefesh should be stringent not to drink any coffee or tea made by a gentile. [Panim Meiros ibid]
 Shach 152/2; Shabbos 51a; Arizal Shaar Hamitzvos Vayeilech regarding Turmisin, even though they are not Oleh Al Shulchan Melachim; Divrei Yosef 45; Maharikash 113; Rashbatz 1/89; Chida in Birkeiy Yosef 113 Shiyurei Bracha 4; Mizmor Ledavid 113; Kaf Hachaim 113/12; Shevet Halevi 6/108-3
 The reason: As when people see him being lenient they will come to be even more lenient than him. [Rashi ibid]
 Kneses Hagedola 113/14; Peri Chadash 113/3; Lechem Hapanim 113/2; Peri Toar 114/9; Erech Hashulchan 113/3; Bach, based on omission of Rof and Rambam, brought in Shach ibid; Minchas Yaakov 75/30; Degul Merivava 113/1; Aruch Hashulchan 113/11; Zivcheiy Tzedek 113/10; Yeshuos Yaakov 113/1
 Zivchei Tzedek ibid; Ben Ish Chaiy Chukas 16; Kaf Hachaim 113/21; Panim Meiros ibid “A Baal Nefesh should be stringent not to drink any coffee or tea made by a gentile.”
 Sefer Hakashrus Lehalacha p. 395